summer_of_alvin :
I bought an Acbel 600W power supply ("85% Energy Efficient"), thinking it'd be enough to run my 2900XT. Since I had no plans to run it in crossfire, I didn't worry/research too much about power requirements. I felt sure 600W from a decent brand was good enough for any single card.
Well, once I got home I noticed that the instruction manual recommends 30A current on 12V rails. Funny, nowhere in the 2900XT box exterior did it say that.
I look at the sticker in my power supply, and sure enough under "+12V1", "+12V2", and "+12V3" is written 20A. I'm using a pair of 2x3 connection pins from the power supply to the graphics card.
Is this going to be a problem?
Hey Alvin. I have never heard of that power supply manufacturer before, but looking at the PDF, the specs look good. I would just use it for a while and find out.
Regarding the +12v rail thing. You have a tri-rail unit with 20a per rail. To get the sustained/continuous amperage on the combined +12v rails, you take the total wattage of the 3 rails and divide by 12. Pretty simple equation but you need to depend on the manufacturer to provide the info. I downloaded the PDF from AcBel and unfortunately they don't list the wattage only mV, which is the same thing Antec does. So I can't give you an exact figure, just a guess. It probably has anywhere from 35a-45a on the +12v rails combined.
Also, just to give you a real world example, my power supply is a dual-rail unit which has 20a on both rails. The total wattage for both +12v rails is 432w which is on the label and can also be found on the Enermax site. So, 432 divided by 12 = 36. So I have 36a of sustained/continuous power on the combined +12v rails. Again, not hard to figure out as long as you know the wattage on the +12v rails and perhaps that's what the 37a is that kpo6969 referred to.
Normally, I recommend either a Corsair or Enermax, but I would try your current PSU out for a while. If you don't have any game crashes or stability issues, your fine. Oh, you should also use 2 - 6 pin PCI-E connectors to power the card. The PDF I looked at says you have 2 since the power supply is labeled SLI Ready.
Here's a link to their site where I downloaded the PDF ......
http://www.acbel.com/html/products_/pc_1.htm
Good Luck