I have just finished a HTPC build, using an intel atom 330.
Ok i am using a mini-ITX case and the PSU sits just above (and slightly asquew) the heatsink which spans the CPU, North & South bridge including the onboard graphics (GMA950). The actual 40mm fan is over the northbridge, as far as I am aware it actually generates more heat than the atom itself!
Problem is the fan on the MB is noisy, (at least for a HTPC), and this is not helped by it directly competing against the intake fan for the PSU which is sucking air into the PSU and out of the case.
I am going to replace the fan with a fractal fan which is 'silent' (SPF 13db), is there going to be any serious issues if I reverse the fan so it goes with the flow? that can't be worse than a 40mm fan try to pull air againsta 80mm fan