Choosing a power supply

Hello everyone
please someone tell me the psu requirements for my specs
like (a minimum of 30A on the 12v rail, a minimum of 20A on the 5v rail....etc)

my specs are:

AMD Athlon X2 6000+ 3.00GHz
2 sticks x 1GB Kingston DDRII RAM
ATI Sapphire HD 2900pro 512MB

please dont attach any online stores links because i cant order through them (I dont live in USA)

Thanks all
12 answers Last reply
More about choosing power supply
  1. You could look into the ACE POWER 520watt PSU.It will run your system just fine.However,if you plan to add more drives or another video card,then I suggest going with someone like THERMALTAKE with their TOUGHPOWER line.They have a nice 650watt that would suite your needs just fine.Other brands to be considered are COOLERMASTER,ANTEC,and REAL POWER PRO.Basically you want 30 amps minimum on either a single rail psu or a multi rail psu(combined).But look for something around 650watts maybe even a 750watt.I only suggest the 750 for future proofing so that adding say 4 more hard drives and a TV card won't adversely affect your system.Goodluck.


    X2 5600+ STOCK (2.8GHZ)
    2X1GIG DDR2 800 IN DC MODE
    ACER 22IN WS LCD 1680X1050
    250GIG HD/320GIG HD
    3DMARK05 15,686
    3DMARK06 10,588
  2. please explain more simply on "Basically you want 30 amps minimum on either a single rail psu or a multi rail psu(combined)"
  3. Look at the back of the box. Somewhere it will say "12 volt max output: 52 amps" (Antec 650 watt TP3) or "12 volt max output: 42 amps" (Antec 550 watt TP3) for example.

    Max 12 volt output will be LESS than the total of the 12 volt rails in a multi-rail PSU.

    Something else to look for is: "Rated at full power at 50 deg. C."
  4. i dont know why i cant understand!!!!

    I need someone to tell me like:

    for 12v : 40 amp minimum
    for 5v : 20 amp minimum

    and so on
  5. Go here:
    The Lite version should be sufficient, and it's free. You can buy the Pro version if you really need the amps per rail. Once you've decided how much you need, then go here: and choose a model from tier-3 or better.
  6. I live in EGypt, we dont have all these brands here, or ANY of those brands.

    SO, i will also need the amperage minimum for 12v and 5v and 3v rails
  7. and I cant get power supply calculator pro, because I need a paypal account to pay, and paypal is not supported in Egypt.
  8. The Lite version should be sufficient. Better power supplies have a good proportion of their power on the 12V rails, where you'll need it most (that GPU in particular needs a lot of power). I put in the specs you gave, and made some assumptions about fans and other things, and it told me 445W. If it were me, I'd find one in the 500W-600W range to allow for future growth, wiggle room, and because PSUs are most efficient and more stable when not working at the top of their capacity.
    If none of the brands from the PSU tiers are available there, one rule of thumb is that heavier PSUs tend to be better. This is because they're made with bigger and heavier heat sinks and larger components. Of course that only helps if you're buying from a store and can pick them up. Price can be another guide. There are a few decent models as low as $60 (e.g. FSP), but if you're spending $80-$120 you're more likely to be getting something reasonable. Hope this helps.
  9. What ever you do make sure to get a top tire PSU listed here:
  10. MicroMina said:
    i dont know why i cant understand!!!!

    I need someone to tell me like:

    for 12v : 40 amp minimum
    for 5v : 20 amp minimum

    and so on

    OK. Let's try again.
    We have two problems here. First, you are really inexperienced. And second, since you live in Egypt, we cannot just tell you, "Go to newegg and order either this PSU or that PSU. Either will serve your needs nicely."

    And I suspect that you have a third problem that I think everyone who is trying to help is unaware of. I am living and working in Saudi Arabia. When I go downtown PSU shopping, what I find falls into 3 categories:
    1. Junk: 50 to 60 Saudi riyals ($15 US)
    2. Inexpensive: 100 to 150 SR ($30 to $40 US)
    3. Expensive: Good brand names which cost about 1.5 times as much as they would in the U.S.

    If you are in that situation, that is bad for you because you are at the mercy of the salesman.

    Before I continue on, two questions:
    1. What brands are available where you live?
    2. How warm does the room (where the computer will be) get in the summer? (Trust me, this is relevant.)

    I am going to assume that you know a little about electricity - watts = volts multiplied by amps. OK?

    If you look at a label on a PSU or a PSU box, THe total wattage will be more than the rating of the PSU. The important rating is the 12 volt capacity.

    Do not worry about the 3.3 volt or the 5 volt capacity. 3.3 volts powers the memory subsystem and the digital part of SATA drives. 5 volts powers the motherboard (except for the CPU) and the digital part of any drives. I have a full featured motherboard, 3 hard drives, and a DVD burner. I would be very surprised if I am pulling 100 watts total off the 3.3 and 5 volt outputs.

    The 12 volt output is the real workhorse. I tend to use conservative, high side estimates (military electronics background). I figure 10 amps for the CPU (15 amps if you are overclocking). And I figure 20 amps for most upper end video cards. Figure 5 amps for 2 or three drives.

    Here is a practical example of what to look for. I just happened to need a replacemant PSU for Box #2, and i just got back to the house and started answering your post.

    I picked up a 500 watt Coolmax (and before the rest of you tell me where Coolmax sits on the Tier List - I know).

    +3.3 v 28A +5 volt 30A +12 volt 18A and 16A Total 12 volt 31A The other outputs do not really matter.

    Antec 550 TP3 (bought on sale for about half price ($45)
    +3.3 24A +5 volt 24A +12 volt 3 X 18A rails total 42A

    For only a 50 watts higher rating, the Antec has much more usable power for a modern PC. The 550 watt Antec would power Box#1 quite nicely. I would not even try to power Box#1 with the Coolmax PSU. And the Antec is rated for full output at 50 deg. C. This is such a difficult standard to meet that any manufacturer who can will tell you.

    Try to get a good PSU. I would recommend at least 40 amps on the 12 volt outputs. Do not worry about the 3.3 and 5 volt outputs. Also do not worry too much whether or not the PSU has a single large rail or multiple smaller rails. One of the best PSU manufacturers in the U.S. favors a single massive rail and will tell you why.

    Also, try to get a PSU that has the proper connectors for what YOU are going to use with it. You can always get adapters, but with a little planning, you shouldn't need to.

    I could have done a short post consisting of the last two paragraphs above. But someone else, with equally good reasoning, could have recommended 30 amps on the 12 volt rails. And you would be confused, "jsc said 40 amps. The other guy said 30 amps. The estimates are pretty far apart. Who do I believe?" But you now know why I said 40 amps.
  11. Whoops. Forgot to check the "Display your signature" box.
  12. thanks everyone for your help, especially jsc.
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