Originally posted by: Narynan
So, I have been looking into getting a Nvidia 275. However, one of the things I am looking at has been the power reqs for this card. It looks like I need 40A for this card. I have the Zalman 850W which has 6 12V rails sticker rated at 18A a piece, meaning hooking up two PIC-E connectors means I only have 36A. However, when I was looking for reviews on the PSU I came across this.
http://www.bcchardware.com/ind...0&limit=1&limitstart=1
That indicated 28A across the hardwired pic-e connectors, which would be more than enough.
Do I have enough power to run this card if I am going to go with a 275?
I think we see this misconception on the board at least 2 or 3 times a week.
The power requirements you are seeing for the GTX 275 is not for the card only. Nvidia is taking into account a moderately high end system that would accompany the GTX 275. That entire system (including CPU, GPU, fans and drive motors etc.) will possibly use up to 40A of 12V electricity.
The GTX 275 draws power from 2 6pin PCI-E connectors and the PCI-E motherboard slot itself. All of those source is allowed to (but will not in this case) provide 75W of 12v power. 75W*3=225W Watts=Voltage*Amps so 225W=12V*x X=225W/12V or 18.75A.
So the GTX is only allowed to draw a maximum of 18.75A or 225W of 12V power from the PSU....as you said it is doing it from three different sources though. All sources COULD be combined on a single rail, All could be on a separate rail, or the motherboard slot can be on a single rail and the PCI-E connectors on another. IF both PCI-E connectors are on a single rail, they are not supposed to draw more than 150W combined or 12.5A
Aynyway, long story short, YES THE ZALMAN ZM850HP IS MORE THAN ENOUGH FOR A SINGLE, OR EVEN DUAL GTX 275