# Power supply question about 7900gto

##### Distinguished
Hi, on my psu it says: +12V1 = 18A , +12V2 = 18A, and under it it says 385W MAX. Its a 585W power supply from safe power. Does it mean that it can handle all cards below 18A+18A= 36A? Is it enough to run a 7900gto, and if not what cards can it handle?

#### Mousemonkey

##### Titan
A 7900GTO is pretty much a detuned 7900GTX which by todays standards is not a very power hungry card, I would still have reservations about using a cheapo generic though.

##### Distinguished
hmm the card requires 22A on the +12v but i have two 12V with 18A, is it safe to say that I have 36A or do I need a power supply with a 22A on a single +12V

#### Mousemonkey

##### Titan
Whilst my maths skills are crap I do know that you can't just add the rails, it is not 18A + 18A = 36A, it's probably closer to 28A - 29A. It' s more a question of, how old is that PSU?, and can it actually supply what the sticker on the side states it that it can?

##### Distinguished
power supply is brand new, the mobo and stuff are pretty old so it wont draw too much power from the psu

#### coozie7

##### Champion
Do n't bet on older tech not drawing much power, the Prescott Pentiums were notorious power hogs and some of the earlier X2 Athlons could chew through 120W with ease.
Mousemonkey is right about the 12v rails, according to the specs you have given the maximum combined output of 385W equates to 32 amps (amps=Watts/volts and 385/12 is 30.083... amps).
According to this site the card draws about 90W:

http://forums.atomicmpc.com.au/index.php?showtopic=264

Even assuming a heavy CPU draw you'll be just fine.
As long as the label is telling the truth.

#### Mousemonkey

##### Titan

I could not remember the formula so I guessed at that without using a calculator, just a skinful of beer!

##### Distinguished
yea i'll give it a try. thanks guys

#### Mousemonkey

##### Titan
No worries, I'm off to get some more beer. [:mousemonkey:3]