i always have a can on my desk, usually open. i also usually have frost on my wall
you dont really have to worry too much about compressed air, if you see your ribbon cables pulling funny you may want to avoid them.
while you clean your pc make sure you get the dust out of the heatsinks and out of the powersupply. in most peoples computers the psu is the only exaust fan and it can get discustingly dirty. (i have a compaq desktop in my closit that has massive dust bunnies in the psu that wont come out, i couldnt even get it open to clean it.)
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