Wait! Don't throw out that old computer that won't boot

The fix can be as simple as a $4 CMOS (watch) battery.

My evening backups failed two nights ago. A ping didn't respond. When I hooked up a monitor, the Windows logo was frozen onscreen.

Okay, no problem, BSOD's or freezes can happen on old hardware running windows. Reboot should do the trick.

I rebooted and the system powered down. It powered back up. The powersupply fan came on... Good. The harddisk and keyboard lights flickered...Good.

But no...now a worse symptom. At this point, reboots either a) froze with a black screen 2 seconds into the bootup, or b) popped up the BIOS settings screen with an error about the CPU being recently changed.

Okay, should not be a problem...will just boot to linux OS on CD via Acronis backup. That'll bypass all Windows and harddrive problems.

But again no...would not boot to CD.

Sigh, time to spend an hour ripping out all the components. Thinned down to the bare minimum: keyboard, boot harddisk, and video card. Removed the extra RAM, the sound card, the extra USB card, floppy disk, even the CDROM.

But again no...would not boot.

Time to call my brother, the electrical engineer.

"Hey Q, I'm about to throw my old server away. I think the motherboard is bad. I stripped everything down to the bare minimum and the system still won't boot to linux on CD. Before I toss it, is there anything else I should try?"

My brother of course had an easy answer which turned out to be the right answer...

"Yes, it's probably a dead or dying CMOS battery. I've seen systems crash just like this when the voltage is below blah, blah, blah. You can confirm with a voltmeter by measuring blah, blah, blah. If that is the problem, then you can pick up a new CR2032 watch battery (that is all a CMOS battery is). They are just $4 at Fred Meyer, Kroger, or a similar store."

Sure enough, I put in the new battery and my system was healthy and running again.

P.S. - When the CMOS battery dies, your system may lose the BIOS settings for CPU type, extra HD info, etc. If enough crtical BIOS settings "change", it can trigger Microsoft Windows to go through a reactivation process. It happened to me...but that is another story.

So, don't toss out that old computer that you think has a fried motherboard...it could just be a $4 CMOS battery.