Annoying POST issue

sychial

I have this annoying POST issue on a clients machine. When the machine is reset, by button or by Windows, about 1 out of 5 times the POST will not complete. It will stop right before it would normally begin its RAM check. You cannot do anything from this point (IE: enter BIOS or other config settings) except hit the power/reset buttons. When it starts doing this, the machine needs to be turned off and turned back on in order for it to complete. The machine runs great except for this little annoyance.

Has anyone come across this before?

Brief history:
The machine originally had a motherboard failure, bad RAM stick, and the gfx card went bad. The board was repaired by the manufacture and the repaired board failed days after installation. A new board, RAM stick, video card and PSU were installed in the machine.

I have done everything from pulling RAM, cards, and running the machine with just the essentials to complete a POST. The RAM has been tested and the CPU has been tested in another machine, they both come back good. The BIOS has not been flashed because it is already the latest BIOS version for the board, and it prevents me from doing so because of this.

Anyone's help and insight is much appreciated.

Strider

Is it possible to tryout the new motherboard in another test machine?

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sychial

Oh man, I'm just sick of removing boards from this machine, but yes, I'll give it a try and give an update. Any reason in particular that you mentioned this? Just curious on what came to mind...

sychial

There was no change in its behavior...

sychial

PROBLEM SOLVED! Well after spending many hours learning a boat load of information about the POST, and it sure was grueling, I started to really think that the CPU may be having a problem... something that I was hoping it wasn't from the very beginning. Being the person that I am, I really hated not knowing what was wrong with the CPU exactly ("exactly" to my abilities since I'm no electrical engineer) if it did have a problem. So upon further investigation I found that there there was a problem with the L1 cache causing it not to purge or clear upon reboot. Only from a hard boot would it clear, which makes perfect sense. I went ahead and disabled it though the BIOS and the problem cleared up... and boy did I test it afterward.

After doing this, I ran some extensive tests on the machine to see if there was any degrade in performance and there was not. I personally do not recommend disabling any type of caching on a machine... yes, and that goes for even you overclockers out there, though there are some temporary exceptions when overclocking. I have informed my client that this should only be a temporary fix until a new CPU is put in, if they choose to have one purchased of course.

Though this problem is probably unique to public knowledge, since I haven't found jack about it and know that hardware doesn't always fail in the same way to have this exact problem for this fix to even work, I hope that some find this information useful and add it to their little bag of diagnostics tricks.