Power but no video signal after BIOS reset

[timrob]

Something strange happened after I changed some BIOS settings for fan management.  Immediately after the change, the computer will start to boot up (harddrive spins, fans turn on, leds on case and dvd's turn on), this happens for about a 1/2 second, then a beep for 1/2 second, then the computer turns off.  There was no video to the monitor, maybe because it shut down so quick.  I knew the problem was the bios change, but at the time, I didn't know how to fix it.

I tried combinations of unplugging and swapping fan connections(2 for case(second is in chipset connection), 1 for PSU, 1 for cpu, heatsink for chipset).  No luck.

I was told to reset the CMOS.  I did this with the same problem.  

I then removed the Zalman FanMate2 controller from the cpu cooler.  I did this and the computer boots up (fans spin, harddrives spin, floppy drive accepts a disk, but now I have no video output(probably from resetting the BIOS).  I confirmed the monitor is ok.  I tried a second video card with the same problem.  I disconnected all peripheral equipment(cables, FDD, HDD, DVD) except for power supply, memory, and video card with the same problem.  I reset the BIOS with no luck.

Any ideas on how to fix this?  Why would resetting BIOS cause no video output.  If BIOS is the problem, if I could get see the BIOS, I could fix the BIOS settings.  My video card has a S-video output which I could plug into a TV, but wouldn't that have the same problem?

Also, when I fix this, is there any utility to print out or export a copy of the BIOS settings to floppy or cd?

[royphil345]

Does your mainboard have a built-in video adapter? My guess in that case would be that clearing the CMOS activated the on-board video. Best way to deal with that would be to unplug your video card with the computer unplugged from power and plug the monitor into the on-board video. Then, disable the on-board video in the BIOS, replace the video card and plug back into it.

If no on-board video...  I'm stumped for now...

Good luck!!!

[timrob]

NO, the mobo has onboard audio only.  The mobo is a  ASUS sock-a atx a7v133a via133a with sound.

[GX1_Man]

Do you have an old PCI video card of any type, low end is fine, to use to resolve this?

[timrob]

Just tried the PCI video card idea with no luck.

The repair shop removed all the components and tested them on another computer and they were fine.  They said the mobo is bad by process of elimination.  I find it hard to believe that changing a fan power management BIOS setting would do this.  I also find it harder to believe the probability of the mobo going partially bad at this exact moment.

Another idea, I replaced 3 plastic standoffs (which were too short and thus useless) with a metal standoff and a paper washer.  A friend said he has seen strange operation when you have poor grounding.  I'm going to check all standoffs and remove the ones with the paper washer.  The paper washer was used because that area of the mobo does not have a metal ring.  I'm also going to swap PSU's, as the PSU case is what provides the ground.  I'm also going to swap the case.  Both the case and PSU are new.  They have been working fine since Christmas.  If that doesn't work, I give up.

[GX1_Man]

You are definitely on the right track with your critical thinking skills. I have seen motherboards grounding out do MANY strange things. Bad MOBO is a possibility too.You are proceding in the correct manner.

[timrob]

Answer found  Kind off

The first tech at the computer shop determined that the mobo was bad, even though he ignored the fact of the possibility of bad/poor grounds, abnormal standoffs w/ paper washers, dirty contacts, a unique cpu fan, and my telling the details of how the original problem happened.  He just ignored the facts.  And I don't think he removed the mobo from the case and PSU, like he should have.  You can't blame something until it is 100% completely isololated.

I complained, told the second tech to check the grounds and completely seperate the board from the PSU and case.  He completely disassembled the board removing it from the case and reassembled it.  While doing this, he found the memory slot to have some crud in it.  Don't know how because I just vaccumed the board during X-mas.  Maybe I'm a poor cleaner  He didn'ts say he cleaned the AGP slot, but I'll assume he did.  Same problem, the computer immediately shuts down.

He then swapped the CPU fan with a regular fan.  (I did this myself, but I didn't clean any of the slots.) He was then able to boot, found, and changed the cpu fan BIOS setting back to default, which should have already happened with the multiple CMOS resets.  The Zalman fan was reinstalled.  Everything works now.

So in summary, dirty slots, non-clearing CMOS, and a fan voltage that caused the resets were the problem.  I think the possible poor ground (we'll never know) was a red herring, but it did force a second look.

[Fed]

There's nothing worse than not knowing what really fixed it. :-?