Possible reasons for CPU spiking?

[bobogs]

I'm reinstalling (cleanly) XP Pro on my old 1.8ghz pc, to see if that eliminates the weird cpu spiking I was getting. It seemed no matter what I was doing, any little task would cause the cpu to spike to 100% and sometimes stay there for several minutes. Open IE7 or Firefox...spike. Browse to a site with flash (video and/or animation only)...long spike. Open Windows Explorer...spike. Run a virus scan that would normally take ~1hr...spike spike spike and it takes 6h.

I'm 99.999% sure I did not have any spyware or viruses, and the hard drives all had plenty of free space. I defragged regularly with Diskeeper, and my 1gb of ram wasn't too shabby. I'm thinking it all boils down to the cpu overheating. Speedfan wouldn't show me any cpu or mobo info, just HDs, so I couldn't gauge the cpu's temp from that. The Dell case's case fan and cpu fan seem to be working, but how effectively I'm not sure.

What options do I have to add more cpu cooling? Can I buy a cpu (not case?) fan from CompUSA, plug in its molex plug for power, and point it toward the cpu? Is it valid to point a fan at the cpu to cool it directly, or is the goal to remove hot air by pulling it away from the cpu? I might try to leave the case open for a bit, with a small desktop fan pointed into the case, to see hwo that affects the performance.

Thanks!
Gary

[nonoitall]

CPU usage spikes when the CPU is being used, not when it gets hot (though it will naturally get hotter as a result of utilization). If a CPU gets waaaay too hot, to the point that it could potentially damage itself, there are usually safeguards in place that will cause it to simply shut itself down. Dell is usually pretty good about making sure that the components in their PCs stay cool enough, even without proper maintenance, and a 1.8GHz Pentium 4 isn't too big of a problem to cool compared to the newer 3.8GHz dual-core Pentium EE monsters that are thankfully being phased out in favor of more power efficient (and thermally efficient) CPUs. Of course, there's no harm in opening up the case once in a while and cleaning all the dust out - that will keep things cooler, but I would say that CPU over-utilization is much more likely to be a software related problem. See if the problem persists after reformatting and reinstalling the OS.

[Krispy Kritter]

You could try looking at the processes tab in task manager to see which program/process is using the cpu during the spikes. You could also check the event viewer (control panel/administrative tools/event viewer) and see if there are any alerts/errors that occur during the spikes. And my first guess, would be a failing HD. I've had this happen recently, and the cpu spikes while the OS is trying to communicate with the drive. While this occurs, you can't do anything until it times out.

[ranchhand]

"And my first guess, would be a failing HD." Good thought, Krispy. Never thought of that, will remember next time a client has a similar problem. I start looking for viruses, "silent" programs running in the background, etc.

Bobogs, as a suggestion, you can go to your HD's manufacturer's website and they usually have a utility to download that will run a diagnostic on you drive and tell you if it is in the process of failing. It may help.