Troubleshooting and Fixing a Dead Pentium 3

The First Sign of Trouble
At the time, I had my computer on 24 hours a day running the SETI@home program. My first indication of a problem came when I woke up one morning and it seemed awfully quiet. I realized that my computer was silent, whereas I would normally be able to hear the cooling fans. The computer had turned off some time during the night.

First Troubleshooting Steps
The first thing I did was to turn the system back on. It seemed to be starting up normally but had not quite finished booting when it suddenly shut down. Okay... the computer is deliberately turning itself off. Let's open up the case, turn it on again and watch it closely. I did that and noticed that it shut down even sooner. Apparently some component was either overheating or simply failing as it reached normal operating temperature. To be sure, I waited a few minutes to let it cool down and then turned it on again. Sure enough, it got almost all the way through the boot sequence. When the system was warm, it shut down quicker.

What Could Be Causing This Situation?
Unfortunately, this problem could be caused by more than one component (otherwise this would have been easy). I felt the prime suspects were, listed in order of likelihood: the power supply, motherboard and CPU. A friend suggested it might also be the video card but I didn't think so. Since I had already been thinking about building a new system from scratch, I decided to immediately buy a new Pentium 4 compatible power supply to see if the power supply in the Pentium 3 system was the cause of the problem.

Replacing the Power Supply
In theory, this is a very simple procedure. In practice, it really is simple but it's also a pain in the neck because there are so many connectors. I bought an Antec TruePower 350 watt power supply and installed it in the Pentium 3 system (which had a much smaller power supply). I started the system up and... it shut down on its own just like it had been doing. grr... Okay, so the power supply isn't the problem. I took out the new power supply and put the old one back in.

Replacing the Motherboard
I figured this was the next most likely part to have failed since it has a couple hundred components installed on it. I bought an MSI motherboard for $61. It was much nicer than the existing motherboard as it could support a wider range of CPU speeds, more memory and had an array of diagnostic LEDs. This last feature was very important to me since it could help locate the problem if it wasn't the motherboard.

Replacing the motherboard is a moderately difficult operation. If you can do this, you can build an entire system since this involves removing and re-installing the CPU, the memory, all expansion cards and a rats nest of connectors (power cables, IDE cables, floppy drive cable, fan connectors and the case front panel LED and switch connectors). I installed the new motherboard and... ARGGHH!!! The system was still shutting down!

Once You Have Eliminated All Other Possibilities...
At this point, I concluded it could only be the CPU that was causing the problem. This surprised me as, based on what I had read and also discussions with a couple of tech-savvy friends, CPUs hardly ever failed. Still, this was my last suspect and I had to go forward. The system had originally had a 733 MHz chip but, with my new motherboard, it could now take a faster chip so I bought a 1 GHZ chip for $99.

I installed the new CPU and powered up the system and... it worked perfectly! This was good since, if the system had continued shutting down, I would have been at a loss about what could have been causing it. So, the system was now working properly and I had effectively 'wasted' the $61 to replace the motherboard. This wasn't too bad since it would almost certainly have cost more than that to have someone else fix the computer.

The New Motherboard Wasn't A Waste After All
Just a few months later, the system failed again. However, with my new motherboard, featuring onboard diagnostic LEDs that step through the start-up process, I was immediately able to determine that the problem was with the video card. I bought a new card for $42 that was more powerful than the original (three year old) card and everything was back in working order.

I mentioned the video card problem to my mother and she asked, "Does it make sense to keep putting money into such an old computer."
I started to compare the situation to car repairs when she interjected that, "You don't keep putting money into an old car.
I said, "Yes, but with a new CPU and motherboard, let's compare it to a car where you've just replaced the engine and transmission. If the brakes fail, you don't junk the car, do you?"
She didn't have an answer to that.

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