Why would my card work in my old pc, but not my new one?

[mfh6375]

My card is a EVGA 8800gt 512mb superclocked. I've had it for about a month, and it has spent that time in my old pc. My old pc is a Dell XPS Gen4 with a P4 3.6ghz HT, 2gb DDR2 4200. The card works just fine in that pc, even though it is obviously bottlenecked.

Yesterday I took the card out and put it in my new build which is a EVGA 750i FTW motherboard, E8500 C2D @ stock, 4gb DDR2 8500, and a Corsair HX620w psu.

The monitor gets no signal when I try to boot the new pc. It just stays in standby. To test the new system, I installed an old 6800. Worked just fine.

So, the 6800 works in both, but the newer 8800gt only works in the old one. Anybody have any idea why this is?

 

[akhilles]

Clear cmos, try each stick of ram in each slot, go to bios, load defaults, up vdimm to specs, install the rest of ram.

 

[mfh6375]

Why would the ram be a problem if it wasn't for the old card? I'll try that, though.

 

[cubeless]

try playing musical plugs with your psu... for some reason i cannot use my bfg 800w psu (4 rails) on my x2 6000/8800gts 640 rig... i get the same problem u have, the screen blanks... a 450w antec works fine (1 rail)... the bfg is fine with anything in my 650sli rig...

i have a feeling it's a problem that jonnyg sees every now and then that if all the rails and the 3.3 and 5v lines aren't loaded then the psu behaves oddly...