PC suddenly won't POST

[sctakeshi]

All of a sudden my PC locked up in the middle of web browsing. I hard-powered it off, and when turning it back on it would no longer POST. I do not get any kind of feedback whatsoever. No video signal, no keyboard lights, no PC speaker beeps. However, everything seems to have power. I can eject the CD tray, hear the HDDs spinning up, and all the fans and lights get power.

The most recent thing I added was a wireless LAN adapter, so I unplugged that first. I unscrewed it and popped it out of the PCI slot, but kind of left it sitting in the chassis so I wouldn't have to unscrew the antenna. Still no POST. The next thing I tried was unplugging all the HDDs. I unplugged their IDE/SATA and power cables. Still no POST. I then tried popping out the two sticks of RAM. I wouldn't expect it to POST without RAM, but I still don't get any kind of visual feedback on the screen. I then unplugged the PCI sound card, and still no dice.

The only things I haven't tried unplugging are the video card (would be a pain to do due to its weird form factor, plus I don't have a spare to test with) or the motherboard/chipset itself. Doesn't seem to be PSU since power doesn't seem to be an issue, but it hasn't hasn't been ruled out.

Any idea before I go buy a PCI video card to test? After that I don't know what it could be other than the motherboard, which means rebuild.

Here are the specs. Feel free to ask any questions that would help you troubleshoot the problem.

Asus A8N32-SLI Deluxe
AMD Athlon 64 X2 Toledo 4200+
HIS X800GTO PCI-express
2048MB G-skill PC3200
three Samsung HDDs: SP0842N, SP1642N, HD103UJ. two PATA, one SATA.
PC Power & Cooling S61EPS 610W
NEC ND-3540A DVDR
Creative Audigy 2zs (there is also onboard sound with the motherboard)
Edimax EW-7128G PCI WLAN adapter
several Zalman fans, and a CCFL
connected to an Asus X223WBD 22" LCD

Built in April 2006, so I hope it still has some life in it.

 

[sivart]

re-seat all devices one at a time and try again.

If you try to POST with just the CPU / Heatsink / Fan and NO RAM, you should get some beep error codes (you will never get video without RAM). If you don't get any beep codes do the following:

1) Check to make sure the PC speaker is still attached
2) Reset your CMOS (jumper, remove battery for a while, etc)

Try again.

Just up and dieing in the middle of browsing and no re-boot sounds like a hardware failure somewhere. Power supply? Short somewhere (something grounding out that isn't suppose to).

 

[mpilchfamily]

Chances are your case didn't come with a speaker to connect to the motherboard. So you'll want to get one connected. There will be a pair of pins in the same group where the case buttons and LEDs connect that is designated for the speaker. Once connected the speaker will give your a series of beeps indicating where the problem is and why the system won't POST. Your motherboard manuel should have a listing of the beep codes and what they mean.

If i had to guess i would say its the video card.

 

[sctakeshi]

Thanks for the help so far. It's very strange that I don't get any beep error codes. The case (Chieftec Dragon) did come with a PC speaker which is connected to the motherboard and until now it would always make a single beep as it successfully POSTed. Now I get no beeps.

It seems like it is not just hanging with an error during POST, but actually hard crashing, as I cannot cut power to the system by simply pressing the power button. I have to hold it down to do a hard-power (or turn off the PSU switch).

I did try removing the video card and still no POST/no error beeps/nothing different. Pretty much everything is disconnected now except RAM, CPU, and power connectors, but I can certainly try completely disassembling it and seeing if I get any feedback with the motherboard removed from the chassis, just connected to speaker and power and nothing else. I haven't had time yet to do this type of disassembly yet. First I will cycle the CMOS...

Any other ideas? Why would there be no error beep codes? This really bewilders me. Is something grounding out the system? But then wouldn't it not power up at all?

 

[pcgeek11]

Sounds like a defective motherboard ( aka Bad Capacitors ). I had a Gateway a week ago with the exact same symptoms.
Carefully inspect the Motherboard and look for leaking or bulging capacitors.

Like these:

http://discussions.virtualdr.c...howthread.php?t=214792

http://forums.mydigitallife.in...read.php?t=1448&page=3

http://loopyfilms.blogspot.com...caps-strike-again.html

pcgeek11

 

[sctakeshi]

Okay, so I removed the motherboard from the chassis and disconnected everything, including RAM. I then set the motherboard on top of the chassis, connected main ATX power, power switch, and PC speaker pins. Pressed power button, CPU heatsink fan spins up but no beeps. To cut power (the CPU fan keep spinning otherwise), I have to hold down the power button or turn off the PSU.

I didn't notice any bad capacitors (good call though), but I guess I have to presume it is the motherboard. I don't know what else it could be, other than the PC speaker being busted. Unfortunately I don't have another case/speaker to test with.

Thanks all for the help so far.