hdtv guy said:
I got a geforce 8800 gtx card and it says that it needs at least 30
amps on the +12v rail. I also got an OCZ 700W GameXStream power
supply. It says it has four +12v outputs and each one is 18 amps. Does
that mean that it has 72 amps on the +12v rail? What do they mean by
rail? I did a little googling and one web site said they used two 8800
GTX's in SLI mode with an OCZ 700W psu.
Rail is just that. What can the power supply put out, at +12V? The video
card makers have suggested hardware requirements for other components in the
system, based on some common assumptions. That is, your video card isn't
the only user of +12V, so the =recommendation= from the video card maker
will be more than the video card needs. If the video card really needs 15A
on the +12V rail, the recommendation might be for a power supply that can
output 30A on the +12V rail, for example.
According to the specs., the maximum power draw of that GPU is about 15A.
But I've read that the card has two PCI-Express power connectors. So most
likely, it will draw a maximum of about 4A from each of two (18A max each)
+12V rails, as it draws some power from the PCI-Express expansion slot
itself (doesn't get all the power from the PCI-Express connectors)
Total draw at +12V might reach maximum 15A, but even that maximum draw is
likely to be divided up between at least 2 or 3 of the +12V rails of the
power supply you chose. You have nothing to worry about. -Dave