I'm looking for power supplies and I've noticed the "SLI Support" spec noted about the PSU (especially on NewEgg). i dont quite understand why a PSU would be "non-SLI" supportive. If it has enough power why would it not be able to run 2 video cards? Any ideas anyone? ASUS P4P800 Deluxe mobo 2 gigs Registered Corsair RAM - 3200/ddr400 1x WD 80GB External 1x WD 80GB Internal 1x WD 160GB External 1x Maxtor 300GB Internal ATI Radeon X800XL 256MB 4

Is it non-SLi supportive, or non-SLi certified? There's a difference.... http://www.slizone.com/object/slizone2_build.html

it says "SLI supportive" check it out, scroll down to the bottom ish. dont really understand it cause it's got 550 watts peak power. http://www.newegg.com/Product/Product.asp?Item=N82E16817159006 asus p4p800 deluxe mobo 2 gigs registered corsair ram - 3200/ddr400 2x 80 gb hdd 1x 160 gb hdd ati radeon X800XL 256mb 420 watt antec dvd-rw/cd rw/dvdrom creative audigy something

Two reasons: 1), wattage power isn't everything 2), high end graphics cards need an extra power plug to plug into them. It is possible that the power supply does not provide these plugs. 3), There is only 22A on the 12 volt rail. depending on the graphics card, they might require more then that. and I bet with SLI, (running two graphics cards), that it will pull more then 22As, meaning that the computer won't run or will be highly unstable. Hope that helps! Please respond after you have solved your problem to notify who helped you and what solved the problem. Both sides benefit when you do.

Just an example, two 7800GT's will pull over 36 amps but only calls for about 350-400 watts depending on third party manufacturer (remember, nvidia doesn't make grahics cards, only graphics processing units. but i'm sure i didn't have to mention that :-P). nVidia recommends 37 amps or higher depending on the manufacturer and how they manage power on the card as well.