Understanding Power Requirements

[phil2415]

Hi everyone, this is my first post here so please be kind!

I've built PCs before for myself but never paid that much attention to the details, figuring that if I bought well-specced enough kit it would all work fine, which it has, mostly.

But this time around I want to do it properly and I'm hopefully putting together quite a nice machine. My question is about power - the one thing I've never really got my head around. I'm looking at an nVidia GTX260 card (216 cores) and I came across this in an article:

"NVIDIA's GTX 260 (and 280) require two PCI-E 6-pin connectors, and a power supply requirement of at least 500W with 36A available on the +12V rail"

Now I'm hopefully getting quite a good PSU, the Corsair 650W TX. This gives 52A on the 12v rail. If the GPU is going to need 36A does that mean that there'll only be 16A left or doesn't it work like that? And if it does, is 16A going to be enough for everything else on the 12v rail? I'm confused! Help!

 

[drunkenmaster]

no, the recommendations are for a suitable psu and ratings for the ENTIRE computer, not just the card. a 650W will be WAY more than enough for any single card computer.

a heavily clocked phenom 2, a overclocked 4870x2, 8gigs mem, several hard drives and fans and under load i never pass 420W, an average single card computer will rarely if ever break 350w continuous load. a 650w would be more than enough for a sli setup for 2x280gtx's.

I think a recentish review put a full load computer with a quad core and 2x 295gtx's(thats 4 gpu cores) at 710W.

 

[phil2415]

Excellent, thank you for the reassurance. Out of interest, you've talked about the PSU being powerful enough in terms of Wattage but where do the Amps come into this?

 

[deshepherd]

Excellent, thank you for the reassurance. Out of interest, you've talked about the PSU being powerful enough in terms of Wattage but where do the Amps come into this?

Power (Watts) = Voltage (Volts) x Current (Amps)