Random Synapses

My computer developed another strange behaviour in recent months. I leave it on day and night most of the time, and just restart it (”warm boot”) every few days, which didn’t give me any problems. But if I shut it down for the night, when powering it up in the morning (”cold boot”), it would reset itself while loading the desktop and system tray applications. And then, the keyboard would not work unless I went to Device Manager and disable then enable it, using the mouse. There was another strange thing: if I left the balcony door open to get some fresh air, the cold winter air would cause the PC to reboot on its own after a while.

It’s been a few months of intense study and work for University graduation, so I had no time to actually fiddle with this until last week, but I kept thinking about the symptoms. What could be wrong? Restarting while loading system tray applications, like the firewall and the network card indicator… Hmm. Could it be a network card driver problem, causing some strange restart instruction for the processor? Maybe the problem was the new VIA Hyperion drivers I installed at the end of last year? Could it be a hardware conflict between the network card and some other component, like the USB 2 controller card and the TV tuner, both installed recently? What did the keyboard have to do with anything, could it be a deffective PS/2 controller on the motherboard? Weird symptoms out of nowhere, just weird. Why would the restart happen only the first time, then, but not the second time? And what’s up with cold air restarting the PC as well?

Cold air and cold boot restarting the computer got me thinking that it was a temperature-related problem: when some circuits got cold, something caused the system to restart. What could it be? An imperfect electrical connection somewhere which stopped working when metallic contacts contracted because of cold air and being cold after staying powered off during the night? Possibly. So I checked power cables and IDE cables for hard drive and optical drives. No change.

I was just looking at the components in the case trying to think of other possible faults, when a familiar image became obvious: swollen capacitors. More than half a year ago I made a lucky discovery that saved my PC, which led to the replacement of 14 swollen capacitors whose electrolyte dried up over the years and they lost their electrical characteristics. Other smaller capacitors on the motherboard were left unchanged at that time. But now, two of them were showing the familiar swollen tops. One was right next to the ATX power connector and the other next to the memory banks — two critical locations in terms of stabilising electricity. Capacitors with dried electrolyte change their electrical parameters based on variations in ambient temperature, so this second discovery was consistent with the symptoms I had observed.

So I went out, bought matching capacitors and replaced these two swollen capacitors. Unsurprisingly, the symptoms disappeared right away. Now I’m determined to replace all these green troublemaking capacitors, when I will be able to find replacements with matching characteristics in stock somewhere. And my next motherboard will definitely not make any compromise in terms of top quality components. The higher price is well worth it.

This entry was posted on Tuesday, February 28th, 2006 at 11:21 pm and is filed under PC stuff. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.