Need casemod advice for external fan (see pic)

Blow air in.

Cut a hole in that plastic, about 3 5/8in. diameter for a 92mm fan. Get a fan, mark the screw holes, drill those out with a 3/16" drill bit. Mount the fan, purchase a filter to put over it to reduce dust intake. If its a tight fit inside the case then mount the fan so its on the outside of the case and you can still screw a filter on to the fan.

http://www.frozencpu.com/cat/l3/g47/c223/s547/list/p1/F...

You could do a 120mm fan too if you wanted.

Thanks.

I realized a potential problem with the idea of using a 92mm or 120mm fan. I was planning to wire up a 5-volt USB powered fan -- mounted on the outside -- for easy removal.

But I'm not sure I can get a fan that large powered off 5 volts. The Dell motherboard has no spare fan headers on the motherboard to be able to use 12 volts, and the power supply is external so I can't tap off the PSU like that.

Ideas to power the fan?

Instead of using a 5-volt fan, my latest idea is to tap off the 12-volt source where it enters the motherboard. Remember, these Dell SX280's are USFF design and the power supply is external.

Unless somebody has a better idea, I was thinking of soldering the fan wiring to the pins, but I don't know which pin is which.