March 20, 2004, 9:41AM

COMPUTING
Motherboard of all problems was just a bad battery
By DWIGHT SILVERMAN
Copyright 2004 Houston Chronicle

I learned long ago that, when it comes to computing, sometimes the fix for a problem is a lot simpler and cheaper than you think.

Unfortunately, it's a lesson I apparently must relearn over and over.

Recent problems with my PC had me on the verge of replacing one of its core components, a process that would have involved days of work, a good chunk of change and a guaranteed increase in my blood pressure.

The solution, it turned out, cost me a trip to Target and $2.99 plus tax.

I thought my motherboard — the main system board to which all PC components connect — was dying. I'd put in an order for a new one and was facing the daunting task of replacing it. Instead, all I needed to do was replace the CMOS battery, a coin-sized cell that allows the system's Basic Input Output System to maintain its settings when the computer is turned off.

I was unaware that a weak battery could cause the kind of havoc I was seeing, and even an engineer and a support technician at Intel were surprised at the symptoms. But once I installed the new one, all my problems vanished.

When you first turn on a personal computer, a feature called the BIOS controls the startup process. The BIOS tests the PC's various parts, such as memory and drives, and begins the process of launching the operating system.

The BIOS is software stored in a type of chip on the motherboard known as a Complementary Metal Oxide Semiconductor. The BIOS has both fixed code that does not change and settings that can be adjusted.

For the settings to be saved when the computer is turned off, a trickle of energy is required. That can come two ways — either through a small amount of standby power known as "flea power" that remains when the system is turned off, or through a battery. In most modern PCs, the CMOS battery looks like an oversized watch battery. In some, it may be soldered to the motherboard, making replacement a task for experts.

Normally, the telltale clue that a CMOS battery is going bad is a loss of accuracy in the computer's clock. You might turn on your computer to find that it's running behind, sometimes by several hours. However, I didn't see that.

Instead, my problems began much more alarmingly. My computer suddenly refused to boot. It would go through startup, and just as Windows XP Professional would begin to load, it would halt, usually before the XP boot logo appeared on the screen. Oddly, I could boot into XP's safe mode.

I tried all kinds of things, from running some built-in XP diagnostics to reinstalling Windows on top of itself. I switched out hard drives, but the other drive — a completely different size and brand — suffered the same behavior.

Jay Lee, who writes the Chronicle's Help Line Q&A column and hosts the call-in show Technology Bytes on KPFT-FM, suggested I try switching my hard drive to the secondary drive controller on my motherboard.

Normally, that's used for CD-ROM drives.

That worked for a while, making me think the primary controller was going bad.

But that setup introduced a new problem — it took forever to boot, and I usually had to try booting up twice. The first time always gave me a "boot media not found" error.

After a few days, I began having the same problem on the secondary controller — the boot process would hang just as Windows began to load. I found if I hit my PC's reset button four or five times, it would finally boot. This was not unlike having to fire up a lawn mower with multiple pulls of its starter cord.

I finally faced up to what I thought were the facts and put in an order for a new motherboard. But then, while going through my agonizing bootup process, the BIOS complained that it had lost its date and time settings, and I needed to input them manually.

After seeing an obvious symptom of CMOS battery failure, I figured it wouldn't hurt to try a replacement. I hoofed it down to Target, grabbed an Energizer CR2032 battery, came home and installed it.

Whoa. Instant bootup. Problem solved.

Testing the old battery, I found it was quite weak. I waved off the new motherboard and breathed a sigh of relief.

I then began to research the behavior I'd seen but couldn't find any references to problems this severe. I even called Intel and spoke with Robert Johnson, who helps engineer the company's motherboards, who said he'd never heard of a similar case. He said I should have seen error messages at bootup that the battery was low, or that my settings were wrong.

He also was curious as to why the battery would fail so early. This happened in a system that is less than 2 years old. Johnson said the battery is only used when the computer isn't using flea power to hold the settings.

Bingo! When I turn my computer off at night, or when I am going to be away from it for long periods, I really turn it off. After letting it shut down, I also turn off the power strip to which it's attached. By doing so, the system drained the battery much faster than normal — it should last between three to five years.

So why didn't I see the telltale signs of the PC's clock losing time? That's probably because I am using Windows XP, which adjusts the system time via atomic clocks on the Internet.

While my circumstance appears to be a rare one, it makes me wonder — how many PC owners have trashed a motherboard or even a whole computer because of similar problems, when all they had to do was spend a few bucks on something as low-tech as a battery?

Probably too many.