2xGPUs=No Windows Bootup.Is it my PSU?

NFL_Psycho · 11 Feb 2006 at 21:01

I've just got a 2nd BFG 7800 GTX OC 256 to sli.Without this 2nd GPU installed my machine runs fine...boots up and runs windows no probs. But when I install the 2nd GPU the MB bios runs but then windows fails to run so it goes to the screen stating windows failed to run, then you can select to run safe mode etc. What I thinking is that my PSU just doesn't have the power. The PSU is an OCZ Modstream 520W. I thought that 520W would be fine when upgrading to sli but I guess not. Is it the PSU thats causing my sli to not work (ie the amp on the 12V)?

NFL_Psycho · 11 Feb 2006 at 21:49

Anyone got any ideas/thoughts on this? I don't wana go n get a more powerful (and expensive) PSU if I don't need to.

NFL_Psycho · 11 Feb 2006 at 22:55

I've tried the cards seperately (both BFG 7800GTX OC) and they both work fine. Both have the same BIOS too. The other hardware using power from PSU are Sound Blaster X-Fi Fatal1ty, Gatewatch Aerocool with 4fans, 4xUV Cathodes (turned them off), A8N-Sli Premium with 3fans, 4x1GB OCZ DDR, and 2xdvd drives.Tried both GPUs with UV cathodes of, Gatewatch n 4xfans off, n 1DVD drive off. Same result as before tho. I think it maybe a lack of Amps on the 12v line. Looks like BFG recommend 12V with rating of 34A or more n I think the OCZ 520W has 12V rating of 28A.

NFL_Psycho · 11 Feb 2006 at 23:54

sli is selected in bios on the A8n Sli Premium. Tried them with out the bridge with no result. At a bit of a loss here.

NFL_Psycho · 12 Feb 2006 at 00:05

Yeah sure did. Even tried without just to see if any thing diferent happened

NFL_Psycho · 12 Feb 2006 at 00:13

Cheers for the advice peeps. I'll give it ago 2moro morning and if I find the cause I'll post it on here. Cheers

NFL_Psycho · 12 Feb 2006 at 10:18

Messed around this morning trying variuos ideas. As it stands both GPUs are installed with their fans a whirling so theyre getting power. Set the ASUS A8N-SLi Premium Bios to Dual graphics setting, fitted the bridge and windows failed to run so up came the message that windows failed to run, select safe mode etc. So I then changed the Bios to single graphics card setting (left the 2nd GPU installed) and windows booted up fine with no probs. 2nd GPU is getting power as fan runs. Just windows wont boot when bios set to dual graphics cards and both card are installed. Anyone had similar problems? Could it be the MB or just a lack of Power for the 2nd GPU unit to actually run?