If you can, explain to him that it isn't hard to remove the side panel and vacuum out the PC. Take the compressed air and blow into the HSF and that should do it for him. I would worry about the small 9600 fan as well. Those L shaped coolers on the XT's are dust traps as well. Simple and routine maintiance will save headaches in the future.
"It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring."
- Carl Sagan
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