Avit av8 system boot problem

I've got a pretty nasty problem on an all-new-build computer.

Had an atx asus Geforce6800 hybrid card (the weird one with GT core and regular mem) and had to mod the molex conn - taking the plastic off- to get an arctic cooling NV5rev2 on as wasn't nvidia reference layout. Tested okay, worked fine for a month or two till my bro decided to shove in a new hard drive, and i think trying to get it in bent the molex wires too far (they were already bent at 45 degrees but worked fine) thus snapping the red one. One fried card. It's definitely dead, i can see scorch marks.

Now here's the screwy bit. After boot with the new hd it worked fine under heavy load for about 3 hours, then died. So hit the reset button, and intermittent, continous, loud beeping - *BEEP* *BEEP* *BEEP* etc, no display signal, and giving me POST code 0.4 which ain't even in the manual. So, being the cautious person that i am, got a friend who works in a repair shop to test all the components, and everything worked fine under test apart from the video card.

So we shoved in an old Riva card that we know works, got it home, and just the same - worked fine for 3 or 4 hours, then died exactly the same as last time and wouldn't boot. Left it alone for 2 days, then tried again - exactly the same thing happened.

I have OC'd in the past but not so much, and sys was running at stock when it died. CPU fan's plugged in, ram's seated properly, fddcable's the right way round and other stupid stuff... we're completely clueless.

specs :

Athlon64 3000 winchester 939
Thermalright xp-90w/ystech 92mm
Abit av8 3rdeye
riva 128 (ex geforce 6800gt/asus v9999)
2xgeil 512mb pc3200 in dc mode
2x maxtor Diamondmax9 80Gb ATA133
500w colorsit psu

V grateful for help or pokes in the right direction :
{sonicbunny}

 

Besides having a messy wired computer with poor air flow, your agp/PCIexpress connector on the board could have been damaged. If you have any PCI expansions, try using a PCI video card.

 

Thanks -
Plugged in a PCI gfx card, no change. I'm RTUing the mobo to see if that solves it. I know it's not a case venting problem, was running casetemps of 27 before i had this problem and used good cable management. Other ideas?
~sonicbunny~