I've been having problems with my computer for the past couple of days. It started out on Friday, I had my computer on, there were no indications of anything going wrong with it...I came back and my computer was off. At first I thought that there had been some sort of power failure in the building but my roomates said no...so I tried turning my computer on but nothing would happen...the power button would flash for a second and the fans would all start to spin up for half a second but nothing...

Now, I had recently had my graphics card, an Nvidia Georfce 7800 Gt RMA'd because it fried...the replacement I recieved was an 8600 GTS. I thought at first that maybe the card had fried, took it out, tried turning it on and it seemed to turn on but the motherboard beeped twice (long beeps).

Anyway, I also had a hunch that it could have been my power supply (450 watts) and decided the next day to go to Office Max and buy a new 500 watt supply for $50 (antec) I unplugged everything, took out the old PSU, put the new one back in and plugged everything back up and again...nothing. It was the exact same thing as described before - without the gfx card in it seemed to work but with the gfx card NOT in nothing happened...

I got an idea and tried running the computer with the card NOT plugged into the PSU and everything seemed to work fine - the card was powered up all fans in the PC were spinning, though the motherboard wasn't beeping when it started up (that might be because I reset the CMOS) - there was nothing happening on the monitor (no, the monitor or cables are NOT dead because I've tried them on other things)

So I returned the new PSU (since I didn't need it) and went to Best Buy and bought a cheap ATI PCI-E card for $50. Anyway, I took the Nvidia card out, put the ATI card in...and it was the exact same effect with the Geforce card - everything worked, card was recieving power, all fans were spinning but there seemed to be no activity. Since I determined that the problem was NOT the graphics card I returned the ATI card (thank god for unopened returns at retail)..

So can anybody help me with this problem? I'm stumped. I've tried everything I can possibly think of and nothing works...I've already been without my computer for a month waiting for my RMA'd graphics card and now I have to go without it even MORE trying to figure this out..this is really annoying. My system specs are below:

AMD Athlon 64 3700+
Nvidia Nforce 4 motherboard
2 gb Corsair PC3200 DDR Ram
Nvidia GeForce 8600 GTS
Maxtor 500 GB SATA HD
Maxtor 60 GB 7200 RPM HD
Creative X-Fi Soundcard
Viewsonic 20.1" widescreen LCD Monitor
Logitech Z-680 5.1 Surround Sound system
Windows XP Service Pack 2

check the BIOS beep guide in the guides forum.

Okay, so I looked over the bios guide...so no beeping means power supply failure...only thing is, I put in the new PSU and got the same thing with the new PSU...

If you have resolved your problem, then you have moved on to doing better things.

I would have suspected another fried GPU (8600gts), since connecting to the GPU prevented the PSU from starting (observed no fans spinning).

Did the ATI video card use the same connection to the PSU?

Having reset the cmos, is there an integrated video on this mobo?

Not all mobo/cmos are created equal in this respect. Some systems automatically select the expansion card for the video (user cannot change this setting or it does not exist). Others honor the setting in the bios.

I know nothing about pci-e. Some mobo's are fussy about the location of the gpu card.