Bad motherboard or bad CPU?

[videohalp]

Used computer. Condition of it prior to my ownership is unknown.

As soon as I plug in the power cord, computer turns itself on. Nothing on screen. The CD-ROM works (physcially). The CPU fan is working. But nothing on screen. No POST either.

I reseated all parts, but the CPU. Swapped all parts, but the CPU. Same thing.

I thought it might be a BIOS problem. So I cleared the BIOS. Tried again. Computer automatically turns itself on again. Except this time...

New problems: CD-ROM not working anymore. Case buttons not working anymore. Case LEDs not working anymore. (Only thing that I see working is CPU fan.)

I cut power through the power supply switch.

What is wrong with this computer? Bad motherboard or bad CPU?

[zoobie]

sounds like you now need to install the mobo drivers to get back to go
sounds like the video card may be kaput since nothings on the screen
look at the mobo and see if any capacitors are bulging at the top...a sure sign of replacement

[videohalp]

That made no sense. How am I suppose to install the motherboard drivers when it would not even boot or POST?

There is nothing wrong with the video card. I have already mentioned that I have swapped all parts but the CPU.

[Nelson37]

Does "swapped all parts" include the Mobo? How about Power supply? Describe change in CD-rom working and not working. Not spinning and the door won't open? Important as bad mobo should not affect this, but bad PS could.

Strip it down to Mobo, CPU, RAM, Video. Completely disconnect all drives, any other cards out. Simplify. Also disconnect all case leads, manually switch using a small screwdriver. Shorted case lead could cause this. Don't forget to disconnect KB and Mouse, also.

Mobo drivers not in play yet. Any beeps at startup? Is there a speaker connected?

Next is remove all RAM, test, then video card with RAM replaced, test. If you got no beep codes, try another PS and test again. If you still get no beep codes, most likely a dead mobo. Further testing depends on availability of parts and cost involved.

[jagabo]

There's insufficient information to say what's wrong. But given the prevalence of bad capacitors on motherboards a while back, a bad motherboard is the most likely problem. Though not by much. Look at the barrel shaped caps around the CPU. Are they swollen or leaking?

[videohalp]

Does "swapped all parts" include the Mobo?

No, because the motherboard is the main part. I can not swap the motherboard nor CPU because I do not have any to.

How about Power supply?

The power supplies are fine.

Describe change in CD-rom working and not working.

No longer receiving power or responding to it at least. Just like the case buttons and LEDs.

Any beeps at startup? Is there a speaker connected?

None. Connected, but condition is unknown.

Simplify. Also disconnect all case leads, manually switch using a small screwdriver. Shorted case lead could cause this.

I will give this a try later.

Look at the barrel shaped caps around the CPU. Are they swollen or leaking?

Forgot to answer when mentioned earlier. No bad capicitors.

No rust anywhere. No melting glue/plastic-like things either.

Basically, the motherboard looks all good physically.

[jagabo]

Note that before ATX power was not switched on and off via the motherboard. You either had to flip the switch on the back of the PSU or the PSU had leads to a separate switch.

[lordsmurf]

I recently had a problem similar to this. I replaced the CMOS battery, as well as the power supply. System is fine again.

[DarrellS]

The case could be the problem. Especially if this is an ASUS motherboard. My brother built a computer about three years ago and the case was the problem. ASUS recommended taking everything out of the case and testing it. If it works out of the case then the case is the problem.

I've used two different boards in that case with no problem but we forgot the ASUS board didn't work and when we put the ASUS board back in, same problems (not sure why the ASUS board has trouble with certain cases). The fan would spin up but nothing else would work. Put the board in a new case and gave the PC to his son. Computer works fine.

[Nelson37]

Is this thing old enough to actually have the switch on the power supply itself, I mean the big red one, with no connection to the motherboard? Some info on brand, processor speed, rough age would be helpful.

WHAT EVIDENCE OR PROOF DO YOU HAVE THAT "the power supplies are fine"??????? Everything is suspect until it is KNOWN GOOD. Brand New is NOT repeat NOT the same as KNOWN GOOD.

Cases and motherboards are not incompatible, mobos which ground against metal are. Removing from case completely good idea, some idiot could have dropped a screw or paper clip inside. Critters another possibility.

The CD-ROM issue is a critical clue. Either the drive is toasted, which would seem unlikely as it worked at first, however it could have died after the first attempt, OR the power supply is defective, which is extremely common and can be variable, OR there is a dead short somewhere, which could be the board itself or its mount, or any device connected to the system, and definitely could change with movement.

Basics - Remove all non-essential parst, do NOT swap. Exchange only essential parts, test with absolute bare minimum - Working PS, mobo and CPU, RAM, video, working speaker. NO kb, mouse, monitor, drives, modem, etc as any one of these could cause failure. If you got a working speaker, no beep codes, and no beep codes after removing seperately RAM or Video, no other testing is needed. Double-check the PS works on another PC, if so, it's toast. Final determination if it is Mobo or CPU requires a tester or swappable part, quite possible both are dead, quite likely neither are worth purchasing.

[bevills1]

Nelson37 suggestions are the way to go. Once I built a new PC that wouldn't post with everything connected, but disconnecting everything except video and memory including all drives, all cards in slots and everything else got it to post. Then adding back one drive or one card at a time and rebooting after each was added resulted in a working system. On another occasion I did same thing with a new system, but it still wouldn't post after which I returned it to place of purchase where it was tested and found to be a bad mobo. If either the CPU or mobo is bad, it may well be necessary to replace both because it may be difficult to find a mobo compatible with old CPU or find CPU compatible with old mobo.

[Snakebyte1]

Could be a corrupted BIOS. Maybe previous owner attempted to flash it and messed up.