Fried motherboard?

[jeece]

Hmm, my PC is acting up.
Specs:
ASUS A7N8X-E Deluxe with Athlon-M 2600 @ 2.4ghz
Mushkin One 2x512mb
WD S-ATA Hard drives
Antec NeoPower 480 PSU
ATI Radeon X800 Pro

This rig is my main machine, up & running 24/24 for years (folding all the time), with the occasional reboot. I woke up one day to find the machine shut down. Tried to turn it on, nothing happened except the LCD screen that would light up for a second then go back to black each time I pressed the Power switch. No fans spooling, nothing. I turned off the main PSU switch, thinking it would help, and when I switched it back on again, the PC powered up by itself! Fans, lights and LCD came on, DVD drive spun, HDs clicked, but nothing was showing on the monitor.

I tried to troubleshoot this. I've switched the PSU for a Vantec unit I had lying around, same thing happens: as soon as the PSU is turned on, the PC tries to start. I've unplugged the Power and Reset switches, in fact I stripped the PC of everything (Ram, VGA, Power Leds...), except the CPU (and its fan) and the issue is still present with both PSUs. I re-assembled all the parts, gave it a try again, nothing improved. I also tried to clear the BIOS with the jumper, and now the mobo is sitting overnight without its battery to be sure. I'll try tommorow.

A good dusting was due inside the case, but temps weren't an issue (temperature monitor was showing "normal", 54-55 Celcius the whole week). While it was stripped down, I removed the CPU heatsink and re-applied thermal paste.

CPU and mobo look all right, no burn mark, leaking cap or visible damage of any kind...

I don't think it's relevant, but I've had my first BAD case of virus on my PC recently (Virtumonde, ZLOB). Had to play inside registry entries and stuff, and system was weird afterward.

What's you opinion on what the trouble could be? Anything else I could try? Thanks all!

 

[RoBo]

I would guess mobo. Put the RAM back in and listen for beeps.

 

[digital_exhaust]

Or.... since it's already apart, start with the basics. Mobo, CPU/HSF, one stick of ram and your video card, PSU, KB, mouse and monitor, and see if it will post. If not, pull the ram, power it up and listen for beeps, and then do the same with your video card. If there are no beeps, your board very well be dead. If the beep sequences are correct, then the component you pulled (memory or video card) could be the culprit.

If all goes well with the bare bones setup, keep adding components until you find the problem.

 

[jeece]

I would guess mobo. Put the RAM back in and listen for beeps.

Good idea. With only the ram and CPU+fan, the PC speaker only emit a faint "click" on power up. After that, there's a very soft shhh (static) sound until I turn the PSU off. It stops when I switch up the PSU.

Scares the hell outta me, but if I leave it running long enough, after 10 seconds or so, the CPU fan and mobo LED slow down/dim a little, like there isn't enough juice available. Then they speed up/light up at normal speed/intensity.

digital_exhaust: will try that, thank you.

 

[jeece]

Nope, computer always power on (but does not POST) upon PSU switch activation, at various state of completion (VGA, RAM, etc). PC Speaker only emit a slight *crack*, then hum very lightly. Only way to shut it down is turning off the main PSU switch.

I tried messing around with the switches (reset, holding the Power one for 4-5 seconds to shut down), the fans always turn at the same speed with no sign of stopping/slowing down.