for the best use of compressed air:
Never spray to close to components; keep your distance. Compressed air can be very powerfull and nock of or damage things if you spray too close to them. Use your own judgement for the distance to keep your can from the PC... This will also solve the cold air problem which some people talked about.
Use, if possible, also a vacuum cleaner to suck up the dust your blowing away. Using compressed air has the big disadvantage that you blow the dust from one part to other parts. And even in a bad case scenario, you blow dust inside components where it will be trapped forever, so be very carefull! For this it is again important not to spray you compressed air to close to the PC and use a powerfull vacuum cleaner to suck up the flying dust...
Other then that, NEVER directly touch components of your PC without a decent anti-static wristband or something (or holding another large metal grounded object like the central heating unit in the room).
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quote:
Originally posted by WDZ
quote:
Originally posted by mwe99
Make sure all power is disconnected
I clean the dust out of my PC while it's running and I'm on the forums. 
* CookieRevised whistles .... 
I'll do it also, but I'm also smart enough to not touch anything while doing it
(but for a very good cleanout you still need to touch, tilt, unscrew, etc.. so power must be off for that though)
/ 
