Im going to be building myself a PC soon for the first time to replace my old box (i think, providing i have enough cash). Hopefully, itll be a pretty decent gaming machine. Im pretty nervous about it, cause it might mean paying for a component, then me screwing it up somehow - and wasting my hard earned cash.
Anyone know anywhere i can get good advice and information regarding how to build a pc with components only. Ive used/programmed computers quite a bit but never really built one, and more often then not i dont understand alot of what the numbers on and type of componets mean. so if anyone has any tips/tutorials or places i can find them please let me know.
Secondly, in your opinion,
is it better to buy the outrageously expensive hardware in hope that it lasts a very long time
- OR -
is it better to buy really cheap components and keep upgrading
Thanks alot guys
RedXVII :U
As for me i would suggest you to wait some time till 2 new platforms appear from AMD - AM2 and from intel - Core 2 (Conroe)... Because you dont find them till late summer/ autumn...
AnandTech.com, XtremeSystems.org etc.
Also my other advice- buy expensive motherboard and cheap processor. It is always easier/cheaper to mov:) to a new processor in some period of time than to a new platform totally changing everything. Also look at new MS Vista's hardware requirements to know the minimum for the nearest future...
Red, there's tons of mainboard manufacturers out there. Whatever you do, don't buy a cheap mainboard! When I first started building boxes I bought a cheap board and had nothing but problems with it. Then I tried an IWILL board, which was okay. Then a Gigabit board, better. Last board is a Soltek and it is great. They are my favorite board vendor now, check them out: http://www.soltek.com.tw/
You can find an unlimited number of system building tips on the 'net. Google it.
Always build to your current situation of need. In the end, the amount of money you have, will over-rule the technical aspect of your choices. I find there's never enough.
Regards, P1 :8)
I'll third the recommendation to start with a good motherboard, regardless of what other components you select. And in my view the key to selecting a good motherboard is to first select a manufacturer that has a reputation for producing reliable trouble-free products. I have had very good experiences with Asus (http://www.asus.com.tw/).
I agree with the idea of making sure you use a class motherboard as well. I long ago learnt that a fast processor alone is not good enough, bus speed, memory speed and a whole pile of oher factors effect how fast a machine will be generally. My 2 PIVs both use reasonably high end Intel boards and they have been glitch free every since the machines were built.
The AMD I own uses a cheap WinFast board with built in video, ethernet and sound card and the video locks up from time to time and I have never been able to track it down but it usually happens when running a browser. When I can be bothered I will buy a higher end cheapie AGP*8 video card for it as it is a reasonably good machine for most tings apart from the occasional video lockup.
I would advise against boards that have built in sound and video as they are rarely ever any good and the seperate cards you can buy easily outperform them and they do not cost all that much if you are careful. I run 128 meg WinFast video cards on both PIVs and they seem to be able to run anything well. As long as it does not have built in video, a server board for a single processor is usually a good place to start as they tend to be built for high data IO.
I suggest an asus nforce (go for the best model you can afford), the're great :U
Asus (video card) was another brand I tried. Pretty good, but driver updates were slow and sporadic and only lasted for a year. Ended up using NVIDIA reference drivers and losing some of the cool card features. It was also a video capture card, and the NVIDIA WDM drivers didn't work as good as the OEM drivers, which was really annoying. That was part of the reason I jumped from the Athlon to Athlon XP. My current slot-A board from Soltek however is over three years old and they are still making BIOS updates for it. :)
Also keep in mind that mainboards, video cards, CD-R's and DVD drives often have update-able FLASH BIOSes. Check the manufacturer's pages every-so-often for updates. Usually this will have to be done from a true DOS window, so keep a DOS boot disk handy.
Thanks for all your advice. I will go for a high quality motherboard from one of the companies you lot have mentioned.
Does anyone know a good place to get hardware from? (Im in the UK btw) I get the feeling ebuyer is good, but its not updated with some of the more latest models (they are lagging by about 3 months), which makes me kinda worried.
Cheers :U
Hi,
I've always used Micro Direct: http://www.microdirect.co.uk/
Ossa
Go for good quality, branded components throughout.
I like Asus motherboards. Is that 3 recommendations for Asus? Must be something in it.
Best value is to go for something that was state of the art about a year ago, that way it's still very good and has a long, useful life ahead but it no longer has the premium price associated with the brand new stuff.
For the main components (Motherboard, RAM and CPU) I no longer plan with upgrades in mind. I'd treat them as a single entity and when it's no longer up to the job, I'd replace all of them together.
Paul.
RedXVII,
Just before you buy, run the list of components with price, by us for a peer review. You be surprised at what we can get for the value.
Regards, P1 :8)
Paul, that's my motto also. Replace the whole box every x number of years.
You could also compare prices at PriceWatch.com. I'm not sure how many UK vendors are listed but it's worth a look even just to compare prices.
As P1 suggested, im gonna run this by everyone. I figured i should go for the best of yesterdays technology as usual. Like, the gamecube and playstation 2's nowdays are mega cheap - i remember when they were blowing holes in peoples pockets.
Right, heres my shopping list, ill update it when people make suggestions/i find out more.
Heres where im at so far... (all links are ebuyer, but its just for the components, ill look around later for cheaper parts)
AMD Athlon 64 3700 CPU Skt 939 (http://www.ebuyer.com/customer/products/index.html?rb=19024720902&action=c2hvd19wcm9kdWN0X3NwZWNpZmljYXRpb25z&product_uid=90949)
Sapphire Radeon X850 XT 256M GDDR3 PCI-E (http://www.ebuyer.com/UK/product/103584)
And from that, i had a wee look at the 939 ASUS cards, im not get SLI so i came to this board...
Asus A8N-E SKT 939 NFORCE 4 AUDIO LAN PCI-Express ATX (http://www.ebuyer.com/customer/products/index.html?rb=19080774427&action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=95458)
Creative SoundBlaster Audigy 4 PCI Soundcard (http://www.ebuyer.com/UK/product/100776)
With this, i can get the OEM for much cheaper, but seeing as i dont know anything about system building, i didnt know if the OEM came with any of those wee wires you have to attatch in the box. Can anyone advise me if this does actually need those wee wires?
After that, i want 2gB of the fastest RAM i could get my hands on. But i got confused looking for "DDR400" when the words "PC3200" and "DDR2" popped up.
Then i went to look at the hard drive. And dont have the foggiest clue what the difference between a IDE, SATA, SCSI drive types.
Also, can anyone advise what kind of power supply ill need? (how the hell are you meant to know this?)
Thanks for all advice so far!
Just a note, not important as you don't want it, but SLI is for NVIDIA graphics cards, Crossfire is for ATI.
DDR is the older type DDR2 is newer, but because AMD does not have it's AM2 stuff out yet, memory manufacturers havn't payed much attention to making decent DDR2 memory yet. As a result, the DDR2 memory isn't performing as well as it should be. Basically, the top end DDR memory is still faster than DDR2, but DDR2 is the future and is capable of scaling much higher... If you were to build your computer later this year, I would say, go for DDR2. However, the DDR is what you should go for now (and, i might be wrong, but the processor and motherboard that you've chosen don't support DDR2). So your fastest memory to go for is DDR-400 (thats what your motherboard supports).
IDE is the older internal standard... SATA is going to replace it. Your board supports SATA - get a SATA drive. (SCSI is something I've never investigated, but as far as I can see, it's mostly used for servers).
Power supplies are fairly easy - choose a good manufacturer and make sure that it has a high enough power rating for all the stuff in your PC... 350W should cover most of it... you might get away with a 300W - I haven't studied your component's power specs much. You work this out by reading the specs for each component in your PC, find the power requirements... add them all up and get a PSU which has a rating bigger than that (and if you might add other bits and pieces later, give yourself some wiggle room).
Ossa
[edit] As far as pricing goes, ebuyer seems fairly similar to microdirect - sound card is GBP 10 less on MD, motherboard GBP 2 less, processor GBP 5 more... not worth choosing MD over ebuyer (and MD doesnt have the graphics card you want) [/edit]
Wow, cheers Ossa. Thats the kinda info i need. asmfan suggested the same thing - wait for AM2 to come out. So i just looked up AM2 and its going to be released fairly soonish, in which case the market will have to rearrange its prices. :green So im gonna wait it out.
The only bad this about this, of course, is i still have to put up with the machine im currently using. Its totally bust, right ear on soundcard doesnt work, distorted lcd picture (fuzzy AND verticle lines, at the edge of windows objects, drawn in the wrong place so gaps appear), it crashes/restarts when i say something funny into the microphone, frequently overheats and its a laptop (so there always a huge compatability issue with most programs, and i get the wierdest lcd resolution ive ever seen). Ive tried fixing it of course, but ive just given up - thats it, into the trash can. I suppose i could hold out for a month though.
I'll post back in a ~month.
Thanks all :U
Quote from: RedXVII on May 16, 2006, 11:30:37 AM
With this, i can get the OEM for much cheaper, but seeing as i dont know anything about system building, i didnt know if the OEM came with any of those wee wires you have to attatch in the box.
OEM parts, nowadays, in my opinion, are okay for basic usage. There was a time when "OEM" was synonomous with "crap" but not so much anymore (there are quite a few Intel "OEM" boards which are quite robust and stable, etc. But generally, an OEM board will
usually include all the wires and connectors and whatnot needed to connect any proprietary ports which are not built-in to the board itself (i.e., like a USB plug and cord if the USB port is not onboard.) Generally though, this shouldn't happen very often.
Quote
After that, i want 2gB of the fastest RAM i could get my hands on. But i got confused looking for "DDR400" when the words "PC3200" and "DDR2" popped up.
The memory requirement depends on the capabilities of the mainboard and the type of board architecture. If I recall correctly, Slot-A boards use DDR memory exclusively, while Pentium boards use PC memory. In any case, the details of the mainboard will stipulate which type of memory you need. All memory types are different and none can be interchanged.
Quote
Then i went to look at the hard drive. And dont have the foggiest clue what the difference between a IDE, SATA, SCSI drive types.
IDE = Standard hard drive. They make these in slower (5200 RPM) and faster (7,000 or maybe even 10,000 now) RPM versions. The faster the disc(s) spin, typically the faster the data transfer rate (but compare the ratings to make sure.) There are quite a few IDE speed standards, the oldest being IDE-33 and the newest being ATA-166 or so. An IDE cable is 40 wires where an IDE-ATA cable is 80 wires, so if you get an ATA-specced drive (probably all you're going to find nowadays) then be sure to get the IDE-ATA 80-wire cable. The mainboard should automatically detect the capabilities of the drive and configure it automatically.
SATA = Serial ATA drive. Uses a thin little data wire, which can help wire routing in a cramped box. Drives are supposed to be better than IDE-ATA, but in real-world performance vs. cost, it might not be worth it.
SCSI = Old hard disk type. Still commonly used, was faster than IDE for a long time. Still has its uses in disk arrays for purposes of redundancy and/or speed.
Disk Array = it's possible to get a board which has a built-in IDE, SATA, or SCSI array controller (usually what is called 2+0 Stripe.) This means that it can take two hard disks and "stripe" data across both at the same time, effectively making data access twice as fast. (In reality it's only like 25-50% faster.) The drawback is, that it's twice as likely for a disk to die, and literally half of every cluster of data will be lost. (Always backup your important data!) Some boards (like server boards) might include a 0+2 array, meaning the same data is copied to both disks simultaneously, for redundancy purposes. This way, if one disk dies, the other is still working.
Quote
Also, can anyone advise what kind of power supply ill need? (how the hell are you meant to know this?)
Experience. :)
Most newer boards use what is called an ATX power supply. Check the board specifications for the type required, then just buy that type. There's only two types, and the older AT-style supply is not as common anymore. The only choice you have is the wattage of the supply, like a 150-watt ATX or a 250-W ATX supply. If all you've got in the box is one (new) hard disk (the newer ones typically use less power) and very little else in the box, use a 150W supply. If you've got four SATA disks, a video capture card, a TV tuner card, and a ton of other extra stuff, get a 250W supply. Many would tell you to just put in a 250W supply anyways. Not many people know this but if you put a 250W supply in a "tiny" computer, it uses more electricity than a 150W supply would in the same computer. This cost can add up over years of operation, and does nothing but help heat your room!
AMD has computer building how-tos which are useful for any topology, check them out: http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_869,00.html
Quote from: Mark Jones on May 16, 2006, 04:40:11 PM
Most newer boards use what is called an ATX power supply. Check the board specifications for the type required, then just buy that type. There's only two types, and the older AT-style supply is not as common anymore. The only choice you have is the wattage of the supply, like a 150-watt ATX or a 250-W ATX supply. If all you've got in the box is one (new) hard disk (the newer ones typically use less power) and very little else in the box, use a 150W supply. If you've got four SATA disks, a video capture card, a TV tuner card, and a ton of other extra stuff, get a 250W supply. Many would tell you to just put in a 250W supply anyways. Not many people know this but if you put a 250W supply in a "tiny" computer, it uses more electricity than a 150W supply would in the same computer. This cost can add up over years of operation, and does nothing but help heat your room!
Mark, these numbers are too low for the hardware specified:
Quote350-Watt power supply or greater recommended
Quoted from http://www.ati.com/products/radeonx850/radeonx850series/index.html
150W is really not good for much with modern hardware... you're looking at 250W minimum for almost anything now-a-days. Just take a quick flip through the detailed specs for newish CPUs (~100W) and graphics cards (varies a lot).
Ossa
This much with power supplies, go for a BIG one as they are far less prone to die on you. I currently use twn fan 500 watt power supplies in a number of boxes and they do last a lot longer. With memory, look up the specs of the board and use what is fastest if the cost diference is not too high. With HDDs, serial ATA is the way to go, I have 2 serial and 2 parallel ata drives on my current dev box and the speed is no difference but serial ATA is the future so i would go that way if the board supports it.
My last comment is if you can wait, do so as this technology is changing very fast and 6 months will make it a different set of rules to follow.
Last night i was doing some programming/gaming. My machine packed in again and its so frustrating. Ive considored that when AM2 comes out, there wont be any processor speed increases till end of about Q3~Q4, which probably mean little in way of price change, which means its not worth the wait for me.
Heres where im at so far...
AMD Athlon 64 3700 CPU Skt 939 (http://www.ebuyer.com/customer/products/index.html?rb=19024720902&action=c2hvd19wcm9kdWN0X3NwZWNpZmljYXRpb25z&product_uid=90949)
Sapphire Radeon X850 XT 256M GDDR3 PCI-E (http://www.ebuyer.com/UK/product/103584)
Asus A8N-E SKT 939 NFORCE 4 AUDIO LAN PCI-Express ATX (http://www.ebuyer.com/customer/products/index.html?rb=19080774427&action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=95458)
Creative SoundBlaster Audigy 4 PCI Soundcard (http://www.ebuyer.com/UK/product/100776)
2x Kingston 1GB 400MHz DDR PC3200 DIMM 3-3-3 (http://www.ebuyer.com/customer/products/index.html?rb=19102721334&action=c2hvd19wcm9kdWN0X3NwZWNpZmljYXRpb25z&product_uid=55296)
I hear kingston is a good maker of RAM - can someone confirm?
Asus TA-210 Mid Tower Case Black/Silver with 360W PSU (http://www.ebuyer.com/UK/product/98548)
This case is for an "ASUS" board right? Well it only supports 1xAGP and 6xPCI slots, is this ok for my board, and with it fit?
Western Digital WD2500KS Caviar SE 250GB 7200RPM SATA2/300 16MB Cache - OEM (http://www.ebuyer.com/UK/product/94403)
This one looks ok - and "SATA2" is mentioned on the motherboard page. So i geuss that will be ok.
Also, of course, a copy of Windows xp...
How am i doing? Did i miss anything? I going buy this by the end of the day if no one says anything.
Cheers :U
Quote from: RedXVII on May 17, 2006, 11:28:37 AM
Also, of course, a copy of Windows xp...
How am i doing? Did i miss anything? I going buy this by the end of the day if no one says anything.
Looking good to me. By the way, you can download (or request a CD copy of) a 180-day trial copy of Windoze XP 64 Pro from the MS website... which
might last you until Vista comes out (but probably not). It will cost you £90.95 (inc. VAT) on ebuyer otherwise: http://www.ebuyer.com/UK/product/97546
You might want a DVD (maybe RW?) drive though!!! Floppy disks are next to useless now, but if you don't have one, a USB flash drive might not be a bad investment (you can always get this later though... wait and see is probably the best course here). I take it you have speakers too? and keyboard, mouse... don't forget these just because they're cheap.
Ossa
The link for XP 64 is http://www.microsoft.com/windowsxp/64bit/facts/trial.mspx - forgot to include that.
Ossa
Quote from: RedXVII on May 17, 2006, 11:28:37 AM
[/url] I hear kingston is a good maker of RAM - can someone confirm?
Yeah, the're good, but imo Twinmos are better, and Corsair are the best :bg
Quote from: Ghirai on May 17, 2006, 12:51:16 PM... Corsair are the best :bg
Yes, they are, when handled properly.
Regards, P1 :8)
Corsair it is! Ossa: thats a pretty nifty idea for windows xp, i think ill be doing that :bg
AMD Athlon 64 3700 CPU Skt 939 (http://www.ebuyer.com/customer/products/index.html?rb=19024720902&action=c2hvd19wcm9kdWN0X3NwZWNpZmljYXRpb25z&product_uid=90949)
Sapphire Radeon X850 XT 256M GDDR3 PCI-E (http://www.ebuyer.com/UK/product/103584)
Asus A8N-E SKT 939 NFORCE 4 AUDIO LAN PCI-Express ATX (http://www.ebuyer.com/customer/products/index.html?rb=19080774427&action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=95458)
Creative SoundBlaster Audigy 4 PCI Soundcard (http://www.ebuyer.com/UK/product/100776)
2x Corsair (VS1GB400C3) 1024MB, DDR400 / PC3200, non-ECC, 184 DIMM, unbuffered, CL3, 64Mx8 DRAMs (http://www.ebuyer.com/UK/product/66405)
Asus TA-210 Mid Tower Case Black/Silver with 360W PSU (http://www.ebuyer.com/UK/product/98548)
Western Digital WD2500KS Caviar SE 250GB 7200RPM SATA2/300 16MB Cache - OEM (http://www.ebuyer.com/UK/product/94403)
About the case, it only supports 1xAGP and 6xPCI slots, is this ok for my board, and will it fit into the box ok? The board has a pci Express slot, and im worried it wont have access to the openenings properly. :'(
Thanks guys for some Nice advice. :U Hopefully it'll be up and running soon, or ill be back here moaning about something gone terribly wrong :lol
Guys, i wonder if advertisement is allowed here?;)
Below i describe my preferences in Brands.
Mainboards - Asus, Gigabyte
CPU - AMD, Intel
Memory - Corsair, OCZ, Mushkin
Video - Sapphire, Gigabyte
HDD - Hitachi
Power supply - FSP
Quote from: hutch-- on May 17, 2006, 05:33:36 AM
This much with power supplies, go for a BIG one as they are far less prone to die on you. I currently use twn fan 500 watt power supplies in a number of boxes and they do last a lot longer.
Huch, it's true you don't want to over-stress a power supply. But also consider this: the cost of residential electricty here (rounded) is 7 cents ($0.07) per KW/h, so a single 0.5KW supply running 24h/7d will consume (0.5KW * 24h) = 12KW/h per day or (12KW/h * 30d) = 360KW per month. At $0.07/KWh that's $25.20 per month or $302.40 per year!
Quote from: Ossa
150W is really not good for much with modern hardware... you're looking at 250W minimum for almost anything now-a-days. Just take a quick flip through the detailed specs for newish CPUs (~100W) and graphics cards (varies a lot).
Yes indeed 150W is too low for a high-end board with fast CPU + GPU or whatnot. I was basing that from the PC's I used to build for industrial control applications where a basic Intel board was used with a newer FDB HD (they consume less power) and dial-up modem - that's it. The HD's were cloned and all configuration and whatnot was handled via VNC so no video adapter or other frills were needed, not even a case fan. It is still possible to build "workstations" this way (albeit, not using a 3GHz processor, but then when programming a simple controller in assembly who needs that?) :toothy A 150W supply in practice worked great in those, and at $0.05/kWh (industrial electricty rates) that costs only $5.40/mo.
Mark,
Quote from: Mark Jones on May 17, 2006, 08:15:58 PM
so a single 0.5KW supply running 24h/7d will consume (0.5KW * 24h) = 12KW/h per day
Only if it is being run at maximum rated output. If you only take 250W the supply will only need to draw 250W + losses. As typical efficiencies are about 70%, this is about 350W not 700W (the 500W you stated plus the 200W you forgot).
Furthermore the efficiency varies with load, tyipically being highest at less than full load and lower at full load
and at light load. The difference may be as much as 10% - 20%. So running 500W PSUs at lower power outputs is not quite as good as it seems.
There are sugestions (on the internet) that efficiencies greater than 80% are on the way!
Regards Roger
Errmmmmm guys..... thats all very well. All I wanted to know was if my PSU 360W was enough. :lol
Well, ive baught it now. How do you tell if the PSU is to low in wattage?
Quote from: RedXVII on May 17, 2006, 11:00:26 PM
Errmmmmm guys..... thats all very well. All I wanted to know was if my PSU 360W was enough. :lol
Well, ive baught it now. How do you tell if the PSU is to low in wattage?
Don't worry, yours is fine... you have an 89W CPU and your graphics card is 75W peak. With the other stuff, you're doing fine with 360W.
Quote from: Roger on May 17, 2006, 09:44:28 PM
As typical efficiencies are about 70%, ...
There are sugestions (on the internet) that efficiencies greater than 80% are on the way!
Wow... didn't realise that they were so bad. I did a switch mode power converter course last year at MIT (6.334), where we took a field trip (the only one I've ever heard of at university!) to a server power supply manufacturer: http://www.synqor.com/ They seem perfectly capable of making 90% efficient power supplies (actually just looked up the spec for a 360W half-brick, 95% is achieved for a good range of loads), which are admittedly much more expensive than PC PSUs, but from what I learned, 80% should be fairly easy to do for PC PSUs, for not all that much money.
Note: I realise that PC PSUs are AC/DC converters and synqor makes DC/DC converters, but many of the same principles apply.
[edit] Seems thay aren't that bad at all actually, for instance this (http://www.fsp-group.com.tw/english/1_product/2_detail.asp?mainid=1&fid=52&proid=363) gives 78% minimum (this was the first manufacturer that I looked at). [/edit]
Ossa
Quote from: Roger on May 17, 2006, 09:44:28 PM
Furthermore the efficiency varies with load, tyipically being highest at less than full load and lower at full load and at light load. The difference may be as much as 10% - 20%. So running 500W PSUs at lower power outputs is not quite as good as it seems.
Hi Roger, you've hit on some of the physical limitations of the engineered topology itself here. But aren't today's supplies better than 80% efficiency? Maybe that is a minimum figure? In any case, putting a 600W supply in a tiny PC is just a waste of power, while putting a 150W supply in a PIV 4GHz might "let the smoke out." :wink
I have not checked recently, but Storage Review (http://www.storagereview.com) used to be a good site for hard disk information.
In the days when I made transformer based power supplies for audio, power consumption was based on load and an idling transformer power supply used almost no power at all but I just asked my older brother who is a whiz in electronics after having been at it for 50 years and he said the later choppers are also very efficient and are smart enough to cut right down on power consumption if the load is very low so I cannot see a reason not to run a big power supply as they are a lot more reliable and don't use any more power than is drawn by the sum total load from gizmos in the computer.
Huch, if my memory serves me correctly, PC supplies are quite different to transformer action. An ATX supply simply will not operate without a load attached because of several factors. PC supplies are switchmode-type supplies which operate by switching a series of inductors "into" the line voltage for brief periods, then "tapping" the stored energy slowly. This is done very rapidly, between 50-500 thousand times per second. The current flowing into the inductors creates an electro-magnetic field there, and physics dictates that the field can either be released quickly (by switching in a large electrical resistance, which results in a higher voltage / lower amperage,) or released slowly into a tiny resistance, which is seen as a lower voltage / higher amperage. A CPU has very little resistance, so the line voltage is essentially "stepped down" into exactly 3.3v or whatnot. The frequency and/or duty cycle of the supply is autonomously corrected to create the precise voltage outputs and changes with load. For example, if all the hard drives are spinned down and system power usage is little, the supply will decrease the "on" pulse period which effectively lessens the power put into the magnetic induction process. When the drives spin up, more power is needed and the "on" period is increased, creating greater magnetic induction and more resultant power available for the devices.
The end result is that there are losses involved with operating outside the supply's engineered "sweet spot." For argument's sake, lets say that a 500W supply, ran at say 85% load, might yield 80% efficiency. But that same supply, ran at 30% load, might be only 55% efficient.
Here's some great data on supplies, along with a shoot-out of various 300-800W models (be sure to see the results!): http://www.tomshardware.com/2005/07/11/stress_test/
Hi All,
Quote from: Ossa on May 17, 2006, 11:55:07 PM
Note: I realise that PC PSUs are AC/DC converters and synqor makes DC/DC converters, but many of the same principles apply.
Its the high volt AC/low volt DC that tends to have lower efficieny.
Quote
There are sugestions (on the internet) that efficiencies greater than 80% are on the way!
Mark: I read this article dated last year. http://www.trustedreviews.com/article.aspx?art=1014 See page 23 for efficiencies.
It is about 5 months earlier than yours and so the products are not quite so efficient. You will see that it is refering to required minimum efficiencies as low as 60% (light load) and only recommends 80% for normal load. Conclusion: Check the specs because not all manufacturers will go for the best.
Quote from: hutch-- on May 18, 2006, 02:02:40 PM
. . . an idling transformer power supply used almost no power at all
As I remember the lectures on transformer design major losses = Iron loss + copper loss. Iron loss also called magnetisation loss is nominally constant over the whole usable power range whereas the copper loss or I
2R loss is dependant on load. In those days (over 40 years ago) small transformers could strugle to get 60% efficiency and, because the Fe loss vector was normal to the Cu loss and load vectors, the no-load input power could actually be higher than the full-load input power. This may be why we now all use transformerless designs :wink
Quote from: Mark Jones on May 18, 2006, 03:44:28 AM
In any case, putting a 600W supply in a tiny PC is just a waste of power,
Not so much power, its more a waste of money. Then again they say 'money is power' so you might be right. :wink :wink
Regards Roger
Waste of power? Whaaat.
If you have a 600W supply and only use 200W in your machine, surely the total power consumption by the machine is 200W, not 600W.
Not exactly. If a 600W supply is 50% efficient (overall) when powering a 200W load, then that supply takes in 400W/h to create the 200W/h delivered. The excess 200W is lost as heat into the room. (This is what is meant by "50% efficiency.") That's why PSU's have fans and cooling panels and radiator fins... to keep them from burning up. :bg
If the same supply was 80% efficient with a 500W load, total consumption would be (500W * (1 / 0.80)) = 625W/h
If it were 72% efficient with a 600W load, total consumption would be 833.33W/h.
A toaster, electric hot-water heater or hair-dryer (generally considered to be the most energy-consuming devices) are about 1.5KW each in comparison. An electric range heating element or microwave oven is about a kilowatt. So the computers of today are becoming big-time energy hogs, especially if they operate continuously.
Roger has an interesting point here, a transformer that is powered on one side and open circuit on the other still has to magnetise the transformer core so there is clearly a load even when there is none added from the other side. To some extent the hysterisis characteristics of the laminations while the power is being cycled at normal AC rates will compensate for the load which will be different from its startup load but there is still a load involved at idle.
The other factor is transformer design has been subject to both better materials and basic design and here I am thinking of torroidal transformers on some of the later silicon steels used as core material. I used to measure the input and output of transformers when building audio and crappy little I and E core transformers produced some strange looking stuff on the output end. The power here in OZ is 240 volt 50 cycle and its reasonably close to a sine wave and with a class transformer the output did not look much different to the input on a dual trace oscilloscope where poor laminations in junky I and E core transformers produced some really weird wave forms.
I used to be able to put a small 2 amp torroidal transformer in the same case as an audio pre-amp and the field leakage was so low you did not have to shield them and they are really quiet in comparison to the best I and E core stuff.
Mark is right here... transformers have very little to do with the way modern PSUs work. They essentially have two parts (although ones even a few years ago had a very different first part, so many are still in use).
Let me just say that there is a measure of how close the current waveform is to the voltage waveform in terms of both shape (i.e. how close it is to a sinusoid) and in phase. The term for this value is power factor and it can be split down into one part for the distortion and one for the phase. The first part is determines the harmonic distortion, and I won't go into the mathematical definition, but suffice to say that the closer it is to 1, the less distortion there is. The phase part is defined as simply the cosine of the phase angle (so if the current and voltage are in phase, this takes on the value of 1). These two values are multiplied together to get the overall power factor. Large industrial companies are often charged by the power companies for having power factors that vary from 1 (as this causes merry hell with the power grid).
Although it's not needed, many modern PSUs still have a transformer at the input before the rectifier... so losses there DO occur, but these are not hugely significant.
The first bit is a rectifier... but now-a-days it's no ordinary rectifier. Lets first look at what used to happen though... basically the PSU would only draw current during the peak part of the voltage wave... this meant that it was in phase, but it had a horrible pulse train type current waveform... so its harmonic distortion was very high. It is for this reason that if you ever (DO NOT TRY THIS UNLESS YOU KNOW EXACTLY WHAT YOU AR DOING) look at the mains voltage waveform on an oscilloscope, you will see that it is a trapezoidal waveform... all these old power supplies are still in use. The way that it varies the power delivered is the length of the current pulses... now, as well as the power factor, the efficientcy of such systems as awful... but it is the power factor that is causing government agencies to introduce new standards that forbid the sale of power supplies that use this type of front end.
New power supplies attempt to control their current waveform, so that it is a sinusoid... I won't go into how, but if you are interested, get hold of a copy of Principles of Power Electronics by J.G. Kassakian, M.F. Schlecht and G.C. Verghese. Let me also say that these rectifiers are very efficient, little of the loss is from this component.
The second is a DC/DC converter (which Mark described nicely a few posts back)... These supplies are called switch mode, because they are split into two circuits, each of which has access to an inductor (or other storage device - a capacitor - but an inductor is the most common), but they cannot "access" the inductor at the same time, so the two circuits are switched in and out of operation very fast... and the ratio of time that each circuit has access to the inductor is called the duty ratio... by varying this,
the amount of power delivered to the load varies enormously. What the system attempts to do is keep the output voltage constant by varying the duty ratio.
So where is the power loss? In several places: the switching components and the storage components... basically the switch has two types of loss: switching loss (from allowing both current to flow and a potential difference accross the device) and conduction loss (from conducting when the switch is meant to be off). The loss in these
is highly dependent on on the power output, but I must make a point here: when switching loss is worst in one component, it often the best in another. The result? switching losses are lower for lower loads, but are proportionally higher, i.e. efficientcy decreases for low loads. The inductor behaves much as you might expect (with copper and core losses) and once again, efficiency will decrease for lower loads.
There is a big note here: the amount that efficiency decreases for low loads does very from PSU to PSU... so if you can get your hands on the spec sheet for the PSU, it will hopefully show you the efficiency versus load graph. But as I said before... because PSUs are made for as little money as possible, they are far less efficient than is possible - 90% efficient (min... max is more like 95%) are possible... just no one makes them.
Ossa