How often do you physically clean the inside of your computer?

[Keitho]

I work on computers in my spare time, for friends and co-workers. I learned a long time ago not to open a computer in the house, because often there will be so much dirt inside, and I don't want it spilling into my house. What I do is take the computer out on my driveway, open it, and blow it out with my leaf blower. That may sound rather harsh, but it cleans all the crap out. I also direct the air into the fans and watch the dust blow out the other side. I've done this dozens of times and had no problems.
As far as my own computer, I just look around inside when I have to open it to temporarily hook up someone's hard drive, etc. It stays pretty clean, so I guess I don't have much dust around it. It is on top of my desk, and not on the floor.

[redwudz]

Just a note: I find it wise to stick a zip tie or other piece of plastic in the fan blades to keep them from spinning when blowing out the dust. It can damage the fan bearings to overspeed them or run the fan backwards. This works well for power supplies that have the fan behind a grill.

A small paint brush or similar is also handy to dislodge dust from some parts while blowing out with air. I use a commercial air compressor myself at about 30PSI. I also wouldn't blow air into a optical or floppy drive as you will just drive the dust deeper. Remove the drive's cover if you do want to blow the dust out to give it somewhere to go.

I would also advise the use of a dust particle mask as you don't want to breathe that dust, even when doing this outdoors.

[TBoneit]

I see computers that look like that come at least once a month for repair. Strangely enough many times that isn't the problem.