I take mine out of the case and vacuum it. Just make sure you ground yourself first.
I store my desktop underneath my desk where I built a wooden shelf to keep it off the carpet.
It gets air from 2 sides for ventilation. I do a cleaning every 6 months inside and outside.
There's a guy who hires out to do it for you...
Make sure he puts some clothes on.
"DON'T USE YOUR SHOP VAC EITHER!"