dead pc.. trying to troubleshoot

[slag]

for the past few weeks, this pc would randomly shut off at night. You could push the power button and it would turn back on and be fine.

after a week or so, you had to pull the plug from the wall, wait 10 seconds, plug it back in, and then restart the pc, otherwise, pushing the power button had no effect.

Fast forward to this weekend where none of the above things worked. Pushing the power button would spin up the fans, but as soon as you let go, all power would be lost.

I ended up taking it apart and putting it all back together. Tried a known good power supply, known good ram, unplugged everything and just had memory, video, and cpu, and now when you try to start it, the minute you plug it into the wall, all the fans spin up but there is no POST.

Removing the memory or video card has no effect--the cpu fan will still spin up with those parts gone.

I've reset the cmos, baked the board in the oven @ 385 for 10 mins, still doesn't work. Tried a known good video card also.. still nothing.. no beeps from the speaker either.

I dont have a spare cpu or motherboard to try. Whats left, short of going to buy a sempron 140 and cheap amd motherboard and throwing this away?

 

[0roo0roo]

rarely is it a cpu
its either psu or mb
looking like mb

 

[Paperdoc]

We had a machine with a similar story - progressively worse symptoms for several days, eventually no workee. Most likely cause was bad caps on mobo.

How old is the mobo? You may recall a series of problems with power supplies a few years ago that all traced to capacitors that were OK when made, but became "leaky" (that is, too much internal conductance leading to heating) and began to fail after perhaps a year or more. Well, the same problem also happened to many mobos of that era, too, but it less recognized. The mobo we have that required replacement (yes, we replaced the PSU first with no improvement) has 10 or 12 cylindrical electrolytic capacitors between the CPU and the back connector panel, and more than half of them show the suspicious "bulged top" symptom. That is the mobo area with all its on-board voltage regulation circuitry. I have a plan of replacing those caps some day and re-using the mobo, which would prove the bad cap hypothesis. Until then I'd suggest you check the mobo for bulgy tops on the capacitor cylinders. If you find some, suspect the mobo and replace it. Unless, of course, you have more drive than I and get busy and replace the caps themserves.

 

[notposting]

Second bad caps, also change the cmos battery some boards are fussy when it is dead/dying. Also hope you didn't bake the battery lol.

 

[slag]

Checked the caps as part of my "normal" inspection of the board and none were bulging. I've replaced caps before and its no big deal to me, but these all _looked_ good. When I baked it, I did take the battery out and when it was done, I tried a new battery I had. No change.

I ended up getting a sempron 140 from microcenter and a Gigabyte board. Unlocked the 2nd core and clocked it to 3.25 ghz. Its running really well. My old board/cpu are still at home. Trying to get someone on CL to buy the combo.

 

[Compman55]

No need to go any further. Scrap the board and move on. CPU's fail every so rarly, you can place a 90% bet it is the MB.