Graphic card and power requirement

[mara-]

Hello everybody,

I'm buying new graphic card. I decided for GTX 460. But, I have one doubt concerning to power requirements. I have CoolerMaster Real Power M520 which has 520W. Rest of my components are in my signature. Now, I think this PSU should be enough when we look at wattage especially since this is 80+ efficiency PSU and since recommended PSU is 450W. My concern is 12V rail. If I figured this correctly from Cooler Master page I have 3x12V rail and each is capable of 19A. For this 3 rails there is 408W reserved. So this does not make sense. If we divide 408W/12V=34A. So, these 3x12v rails can't give together 3x19A. But, my main question is will I be able to run this graphic card on this PSU? I read somewhere that it needs 24A. This card requires 2 x PCI-E 6 Pins connectors, so will that in combination give it enough power? What do you think guys?

Cheers ;)

[LeetPirate]

It will work. The max specification is 20A max per rail, anything more will just cause increased noise and heat and possibly burn out the wire. I know the math doesn't add up to 408W but that might be because the Amps rating is from the apparent power which is actually 240VA per rail as per the ATX specification and the 408W is only the real power. 240VA / 12V = 20A max per rail. It also means the combined output of all the 12V lines cannot exceed 408W, and also bear in mind it does say 19A peak current per line but they don't disclose how long it could actually sustain this peak load current.

Every manufacturer of psu uses their own methodology to come up with these figures and they all try to mislead you in some way, like for instance they often calculate the MTBF at 25C which is an unrealistic temperature, inside the PSU could never be that cool. Cooler Master is actually my favourite brand for power supplies, they are more honest in their specs in my opinion.

The GTX460 is not so power hungry, my friend used it on a Cooler Master Elite 460W which isn't even 80plus certified and it worked. Just connect power it from separate lines and everything will be fine, I see you psu comes with 2 PCIE 6 pin connectors already so this should not be any problem for you. You could check the benchmarks for the card, most I have seen suggests the GTX460 uses less than 200W peak.

[mara-]

OK, thanks for explanation. I also did some more investigation, and this PSU should give combined 34A, so it will be probably fine. Card is ordered, so we'll seen soon.

Cheers ;)

[LeetPirate]

According to Guru3d, the card should average around 154W with 100% GPU stress. I trust Guru3d more than the other sites.The highest OC edition they had was the Palit Sonic Platinum gtx 460 and they said it only used approx 175W so you have nothing to fear.