Motherboard dead?

[Spiv]

Hello All. I am fixing a friend's computer and here's what's happening:

She says it won't boot. I get it and it boots fine, so I go in and start to clean up the huge amount of spyware and viruses that are on the machine. I get a few but while I'm running Spybot the system just shuts down. Or rather, the fans are all still going and the harddrive is still powered (i.e. spinning), but the screen is receiving no signal and no visible work is being done. The harddrive makes no usage noises, the power light on the case is off, and nothing responds, not even the reset button.

So I hold the power button in and the fans turn off. I turn it back on and the same deal: fans spin up, everything appears to power on, but no boot. Apparently this is what she experienced too before she gave it to me.

I swapped out the cpu for my old northwood p4 (it's a socket 478 board that had a Celeron in it). Same deal. I take out the memory, no beeps. I switch power supplies, same deal.

To me it seems as if the motherboard has died. Is this a correct assumption?

And if so, what do you recommend for a gameplan? Replace the mobo, or just get a whole new system? The system is getting a bit old, but upgrading would mean a new processor, video card, and memory.

 

[MarcusL]

Are you able to get into BIOS? Might want to hit the "reset to factory defaults" option if you can get there.

If you are not getting to bios, (looks like you already tried some of this, but I'll just include all standard debug steps)

1) try a different power supply
2) try different video card
3) check for hot components (bad fan? dust buildup? dried-out thermal paste)
4) disconnect all unnecessary hardware (hdd, cd, dvd, floppy, sound card, etc) Get down to psu, cpu, mobo, ram, and video only. If you cant get to bios in this stripped down mode, you'll have to start replacing items
5) reduce ram to one stick (rotate through all of the dimms one at a time to see if one is bad)
6) measure voltages with voltmeter (cpu, memory, northbridge, southbridge, 12v, 3.3v) maybe a voltage regulator on the mobo is going bad (dried out electrolytic caps or something)

You mentioned there were viruses, there might be one that corrupted the bios. You could buy the cheapest mobo you can find off ebay to see if it is the fixes the problem.

 

[Dumbguy]

I had similar issues. If I would do something (like open a large .jpg folder) it would lock. No keyboard, mouse or even a screensaver after 10 minutes. Just lock.

I replaced the mobo and it's all happy. I was testing with memtest and it came back with RAM errors on test 7, but I swapped boards anyway (excuse to upgrade). I've been using the same memory and have had no problems at all.

 

[daduke]

1) I would try to boot into safe mode (F5), if you get into safe mode then the finger would point at the video card drivers as being corrupted. Driver cleaner pro (drivercleanerpro.net) is free and does the best job of cleaning out old drivers.
2) If your using her monitor when you brought it over to your house try a different one to see if thats what's on the way out.
3) Also look closely at the capacitors on the side of the CPU (tall cylindrical looking objects), there will be quite a few throughout the board. It's not unusual to see 10 or more. Anyway look at the bottom where they meet the motherboard and see if there is a brown looking stain, very similar to a leaky battery. If they're bad they can also be bulging on the top like there ready to explode (they should be flat on top). If this is the case the problems you experiance are common to bad caps, spuratic screen boots and then finally no boot to the monitor at all even though every thing looks like it's running normal. I just had the electrician at work replace 10 bad caps on a customers computer and it worked great after that. I ordered the capacitors from digikey.com after he un-soldered them so I could see the voltage and the uF rating located on the side of the caps. Also measure the diameter of the caps with a caliper and try to match the size if they are mounted close together. If you decide to try this and go to digitkey to buy them do a search for capacitors and then the sub catagory Electrolytic, these are the kind that can be used on motherboards. They will cost about .75 cents or less generally. This will take some very fine soldering thats why I brought it to our electrician because you can't have any soldier touching any tracings (embedded copper wire like paths) on the board.
On the other hand it may be easier to just by a new motherboard but not as fullfilling.

 

[Spiv]

Thanks for the suggestions guys. I'll just clarify some details.

I'm using my own monitor so it's not the monitor.

I dusted the system before beginning, so it's not dust/overheating.

I tried a different processor/hsf so it's not thermal paste drying up

It does not seem to make any attempt to boot. No POST, no beeps, nothing.

I checked the caps on the board, but they all look fine (no bulging, leaking). That doesn't mean some aren't bad, but at that point I'd rather replace the board than solder on new caps.

If a virus corrupted the BIOS enough to have it not boot at all, then I have no way of flashing a new BIOS, as the system won't even POST (correct me if I'm wrong here, but no BIOS = no floppy access, right?)

I haven't checked voltages on the board, but again, as with the bad caps, if a voltage regulator has gone bad, it's best to just replace the board.

As far as the standard debug steps go, I've done 1, 3, 4, and 5. A bad video card usually beeps, doesn't it? Anyway, I'll try that tonight, along with swapping out the RAM (but even with no RAM in at all it didn't beep).

I have not run Memtest, but I will try another stick of RAM to see if that's the problem.

 

[Qeldroma]

My computer was randomly restarting like that. I found out one of my Dimms was bad. I had 3 sticks of ram in there, I restarted with only one and let it run, then I swapped it to each dimm. Ended up being my last dimm was bad. So I just dont use that dimm.

But try the video card. I dont think it will help because it doesnt sound like its even booting up to that far.

Good luck.