Suddenly non-booting, non-posting PC

[uluru29]

My PC has been running fine since I built it a year ago (specs below). Today, I shut it down and turned off the PSU switch before removing a sound card I wanted to look at. I took it out without incident, saw what I needed to see (checking what opamp it uses) and put it back in. I turned on the PSU and the case power switch.

The power light comes on, fans and drives all power up. But there's no video and no evidence the PC is booting - the lights on the USB keyboard do not go on, no beeps. My Radeon 4870 has 3 red LEDs that start blinking suddenly, then it revs the fan a little, then they blink, then rev the fan, over and over. I check the PCI-E power connectors, and reseat them, to no avail.

I do some searching and see that this can be a sign of a failed card, or bad power supply. I try another video card that's known to work; it does not have any diagnostic LEDs, but the same basic thing happens - no video, no boot. So I try a different PSU - I plug in the 24-pin cable, and the 4-pin CPU plug, and leave all drives unplugged. This causes the same thing; fans spin up, power light comes on, but no video, no beeps, nothing. I end up using my multimeter to test my original PSU (Enermax) - all voltages measure properly on the 24- and 4-pin connectors.

I've also tried removing and re-inserting the RAM - I tried the 2GB pair in the first slots with the 4GB pair removed, but this didn't work.

Unless I'm missing something, it seems at this point my motherboard might be damaged. Any other suggestions? Again, this setup has worked flawlessly for about 1 year until tonight.

Components:
AMD Phenom II X3 720 w/ Noctua heat sink (overclocked to 3.2, temps typically 30C idle, 40C load)
Gigabyte MA770-UD3
6GB GSkill RAM (2x2GB, 2x1GB)
Two WD Sata2 hard drives
1 Sata2 DVD burner
Linksys Wireless network card
Emu 1212m sound card
Enermax Modu82 625W power supply

 

[pcgeek11]

Go back to the basics:
1.) It was working.
2.) You removed the sound card and reinstalled it.
3.) Now it doesn't work.

Hmmm.
Look at the sound card and see if it is properly seated.
Try and boot without the sound card ( maybe it was damaged by Static ).
Make sure you didn't dislodge something else when removing / reinstalling the sound card.

 

[uluru29]

I have tried booting with only the video card (the one I swapped out that's confirmed to work), and no other cards, but nothing..

I get the impression the PC does not even advance to the point where it would care what cards are installed - it won't even "post."

There are only so many things that could be dislodged - the only ones that would actually prevent the pc from starting at all are the power connectors, and those are checked. I have unplugged and replugged all SATA connectors - and tried it without any drives connected. Nothing seems to work.

Gah...I might actually be forced to drop this thing off at Best Buy or something - it's probably too involved to get diagnosed over forums, like I have been able to do with past issues.

 

[pcgeek11]

Do you have a PC Speaker?
If so does it beep at all?

If not get one and report back the beep code.

 

[uluru29]

My motherboard has a built-in speaker - it usually beeps once when starting up. It is not beeping at all. This thing is seriously dead, NO activity whatsoever. I know the PSU and video card work, I tried them in another computer in the house, and they're fine. The board has everything it needs and will not turn on in even the most rudimentary way.

Thanks for trying to help, but I've ordered a new mobo. Even if my current one magically works again the day I get the new one in the mail, I won't be too upset...it will be nice to have the new one for some features I've been kind of missing (firewire port, ACC). Still kind of sucks though. Thanks anyway!