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View Full Version : twin 12V psu rail question.

rob-beddall
07-03-2009, 06:47 AM
hey,
I'm currently having a few problems with my graphics card and I suspect it may have something to do with the PSU not supplying enough juice. (I've tried all other possible alternatives)

Firstly the graphics card (9600gt) states that it needs 26A on the +V rail. (I've done some research into PSU's and sort of know what this means)
The problem is that my PSU has 2 V rails, 18A and 17A. does this mean that the card is going to be unstable? ( from my understanding it does, I just want to check)

secondly, how do I know which Rail the card is using? or which rail the other stuff in the case is using? ( there is no colour key on the PSU itself, and it's a pre-built computer)
would the 2 seperate rails have different coloured wires?

any help would be greatly appreciated.

cheers.
imashination
07-03-2009, 03:04 PM
The wattage and brand of your psu?
rob-beddall
07-03-2009, 03:07 PM
hey,
Not sure of the brand but the wattage is 550W.

cheers
olson
07-05-2009, 04:59 PM
If the power supply has two 12V rails, one 17A and one 18A and the card requires 26A then that power supply won't work. Chances are it supplies one of those rails exclusively to the motherboard and one for the rest of the devices in the system that use the Molex and video card connections. This is one of the problems in buying a multiple 12V rail power supply you don't know where each rail goes and devices that use more power than the rail can provide are unusable. Multiple smaller rails are cheaper to make than one large rail so most middle and lower end power supplies will have two, three, four, and even five 12V rails.

Two things, are you sure the card requires 26A on the 12V to run? That sounds like a lot for a middle range card. If it really does need that look for a larger single 12V rail power supply. Some models from Silverstone and Corsair are large single 12V rails and all from PC Power & Cooling are. The 750W Silencer from PC Power & Cooling is one of the best power supplies for the money. Cheers!