PC shuts down immediately after POST

By Rossputin
Dec 14, 2007
  1. Hello all,

    My homebuilt PC, which has worked fine for a couple of years, suddenly isn't working after I cleaned out the pounds of dust from inside it.

    During POST process, the BIOS/RAID controller seems to identify the hard drives properly (I'm running two pairs of RAID-1 mirrored SATA drives) ...and I think it's not the drives anyway because of the last bullet-point below.

    System goes through the BIOS part of the startup without problems but then either shuts down or reboots almost immediately:

    * If I try to boot into windows, it shuts down after a couple seconds of the "blinking light" moving from left to right on the first Windows screen.

    * If I try to boot into safe mode, it shows a long list of drivers on the screen, the last of which I believe is mup.sys, and then says at the bottom center, "press ESC to cancel loading VAX347B.sys", and then crashes. I doubt that VAX347B is the problem, however, because of the following:

    * If I disconnect all hard drives from the system and boot from a Windows XP CD, it shuts down or reboots when screen says "Windows is inspecting your hardware configuration."

    During the cleaning process, I removed the CPU fan, cleaned it and replaced it. Someone suggested to me that if it weren't back on exactly right, that could cause the problem so I took it off again and put it back on and the computer then worked...for two days...after which all the symptoms returned. I don't believe it's overheating because the crash will happen 15 seconds after starting a cold computer (though I suppose that doesn't mean the computer couldn't think it's a heat issue.)

    When I was restarting the PC after the original cleaning, I thought I heard my UPS make an odd noise as if turning on the PC caused a sudden (bad) power draw...and I thought I smelled something burning. It was very faint. I moved around some cables and tried again and that issue went away, but that certainly could have caused a problem...I just don't know what problem.

    When I boot into BIOS setup, the computer will run without stopping. When I go into the BIOS monitor sections for voltage and for temperature, all readings seem to stay within very narrow and normal ranges.

    Any thoughts on this would be GREATLY appreciated!

    Please respond to group and, if you can, to me directly at rossputin (at)
  2. Tedster

    Tedster Techspot old timer..... Posts: 6,000   +15

    CMOS battery probably needs changing. Also check the PSU with a tester and a multi-meter.
  3. Rossputin

    Rossputin TS Rookie Topic Starter

    testing PSU?

    Could you please tell me how to best test PSU with multi-meter, or maybe give me what you think is a link to good instructions?

    Thanks very much!
  4. Rossputin

    Rossputin TS Rookie Topic Starter


    Computer won't even boot now. I tried Memtest86 and it seemed like it worked with one DRAM in any slot but not with any combination of 2 DRAMS in any 2 slots.

    I created an "Ultimate Boot CD" to run some tests, and each time the computer would shut down a few seconds earlier.

    Now it won't boot at all. I get a post code 90 on the ABIT motherboard very fast, and the CD-R light is on but it just hangs. Also no video comes up on the screen.

    When it did boot the prior time, it seemed to me that the ABIT uGuru utility was measuring a very high CPU temp, something around 178 F or 81 C.
  5. Condor

    Condor TS Maniac Posts: 388

    You might bump and loosen some wire.
    as for the cleaning , i always bring my PC to a pro to do it for me =]
  6. CCT

    CCT TS Evangelist Posts: 2,653   +6

    For people reading: he took the cpu cooler off TWICE! Did he clean off the old paste and apply new paste (a thin film). Did he check the heatsink was firmly attached (no loose 'legs')?
  7. Tedster

    Tedster Techspot old timer..... Posts: 6,000   +15

    check your output voltages off your rails. Before you use the a multimeter, you need a PSU tool with multimeter outputs. Plug the meter into the tool- it will tell you what the appropriate voltages should be UNDER load. A good tool costs around $10 -15 at an electronics shop.
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