Computer Won't Always Post

[mphartzheim]

Alright, I'm trying to fix my roommates computer, so I don't have all the information.

Computer was working normally (as far as he tells me) until today. When he tried to turn it on today, it wouldn't. The power would come on and all of the devices (cdrom, keyboard, monitor, mouse, etc.) would power on... but the OS would never load. That's when he called me into the room.

Turns out that the motherboard wasn't posting. I knew there was some sort of electrical or motherboard problem. The lights on all of the devices would flash on and off, as if they were losing power constantly. My first reaction was to clean all the dust out of it because it was dirty. Amazingly, it posted and booted after that.

Problem solved, I thought. So we closed the case and hooked everything back up and turned the computer on again... and it wouldn't post.

Right now the computer is up and running, it seems it will post and boot randomly. More times than not, it wouldn't post.

Any ideas? Could we have a failing power supply here? This computer is around 5 or 6 years old and has not been significantly upgraded since it was purchased. It's possible the computer is just old and dieing.

 

[Atheus]

It is very likely the power supply, especially if it's 5-6 years old. Hard disks will be nearly dead too I expect.

 

[mphartzheim]

Is there something inexpensive I can buy to test the power supply? Such as a volt meter?

Or would unplugging unnecessary things from the PSU help test that? He's got dual cd-roms, if I unplugged both of those it would draw less power and (theoretically) boot up more reliably.

 

[mphartzheim]

Update:

The computer lost about 5 minutes off the clock overnight (this is running Win2k, it doesn't sync with an online clock). To me, that suggests that there is either a voltage issue (lower voltage would cause a normal clock radio to run slow, could do the same with a computer)... or there is something wrong with the motherboard, the battery maybe? I don't think the motherboard battery would cause the boot problems OR cause the computer to lose time off the clock while it's running. I could see a failing battery slow the clock if the machine was turned off, but it wasn't off overnight.

 

[BadThad]

Try reseating EVERYTHING connected to the mobo....don't just feel that it's tight, pull it off and put it back.

 

[Cdubneeddeal]

Originally posted by: mphartzheim
Update:

The computer lost about 5 minutes off the clock overnight (this is running Win2k, it doesn't sync with an online clock). To me, that suggests that there is either a voltage issue (lower voltage would cause a normal clock radio to run slow, could do the same with a computer)... or there is something wrong with the motherboard, the battery maybe? I don't think the motherboard battery would cause the boot problems OR cause the computer to lose time off the clock while it's running. I could see a failing battery slow the clock if the machine was turned off, but it wasn't off overnight.

The CMOS battery would do that believe it or not. If the clock is running slow or losing time, then the CMOS battery is to fault.

 

[mphartzheim]

So... the CMOS battery could cause a clock to lose time even while the machine is powered on? Didn't know that... but still, would the CMOS battery cause the unit not to post? And to cause all of the fluctuating power problems that it appears to be having?