Is there a way to see or detect if capacitors on a motherboard are bad? Is it possible for them to be bad, but where you can't see it on the outside? Is it possible to replace bad capacitors from a motherboard and use it again afterwards?

Quote: Original post by DJHoy
First of all, I'd have to ask - why are you thinking you might have a bad capacitor or two? Is your motherboard having any specific problems, or, is it a more general question..

This is about the computer I've been having for 5 years now. Recently I've built a new computer, but I still need this old one.

This old one has been showing problems already since it was a year old. Very sometimes there was a sudden random crash for no reason. There have been times when it was about once a day, and then there were periods when it hasn't shown any problems at all for many months, and then later randomly it did it again. It was OS-independant, so certainly not driver dependant. I did a memtest, and made the memtest run for a whole night, and there were 0 errors. I then always suspected the videocard, because the errors were usually video card related (video card drivers mentioned in the crashlogs).

Then about a year ago, it had a different kind of symptom: sometimes when booting up, the motherboard started making a sequence of low/high/low/high/... pitched beeps. Pressing the reset button made it boot up fine then. Since there was that easy solution of just resetting, I never really did anything about it. After about a month, that beeping problem disappeared again mysteriously.

But now the computer is again in a bad period. Now, when booting up, I can go to KDE in Linux, and after a minute it'll freeze. Then I reboot again, to KDE again, after two minutes, it freezes again. I also tried it with booting to MS Windows, and same thing: it freezes after a while. Sometimes it also reboots after being frozen for a few seconds.
Then I was like, let's look in the BIOS at the temperatures. So I boot to the BIOS and all voltages and temperatures look normal. But then, it freezes again. My computer actually managed to freeze while in the BIOS menu :)

I've mentioned all these freezing problems, but after rebooting enough times it'll stay on without freezing for more than 5 minutes, and then it remains on and is rock-stable.

That made me think that it's not really a faulty RAM, not a faulty video card, or bad CPU, but some electronic component that appearantly is sometimes unstable and after a while settles in and works longer, or maybe isn't needed anymore once a certain temperature is reached or so. And so couldn't that be a bad capacitor on the motherboard?

BTW if it is a bad capacitor, is there any danger that other components may get damaged if I keep using it?

I haven't found any leaking or imploded capacitors, so maybe they're not the problem after all, luckily (or not because no obvious cause is found).

I've given the computer a very thorough vacuum cleaning job. There was a lot of dust indeed but nothing that seemed to cause short circuits. It hasn't crashed yet today, but that doesn't mean anything with this really unpredictable computer, it could as well crash just after I made this post :)

EDIT: yup crashed again now, same symptoms. Stupid machine.

[Edited by - Lode on September 8, 2007 3:24:22 AM]

This thing is making me crazy.

The power supply isn't really the best one indeed: 300W, made in China, brandless.
However if I look in the BIOS hardware monitor, the voltages are all normal. If the voltages are normal, it's ok, right?

If I look in the BIOS at the voltages sometimes it freezes too. But the frozen voltages on screen are still all within the range. So either it's not the power supply, or it's the power supply but something else than the voltages (is that possible?), or the voltage really becomes out of range but the BIOS doesn't react fast enough to show this on screen before it's frozen.

Here's some of the things that happened yesterday and today:

I boot up, work in KDE for 20 minutes, then suddenly it freezes and my music is stuck in a loop. It auto reboots then after a few seconds.

I go to the BIOS menu to look at the hardware monitor to see the voltages. The BIOS shows voltages that are all in range. I press a key on my keyboard and notice that the BIOS doesn't respond to my keyboard! It's still updating the values on screen, but yet there's no response at all to the keyboard anymore!

I press the reset button, and the screen remains black with its power light indicating standby. I turn off the power a few times, and after a few retries, the computer boots up again, in KDE again.

10 minutes later, while I'm compiling some code, it freezes again! I press reset again and the screen remains black again. I press reset many more times and after a while it boots up again and I'm now able to type this text on it.

The weirdest, new, thing, now is that the keyboard wasn't working while the screen was still updating with new values in the BIOS. What can that indicate?

Another new thing is the black screen when rebooting :(

I really hate this kind of unpredictable computer problem, WHAT IS THIS?

Luckily, I use this dreaded machine only in the weekends when I'm at my parents place, but still...

I will try a new power supply if I have one available.