I've built a HTPC using CiT MTX-001B
I've set the stock PSU aside and running it with a PicoPSU variant so that there's only the stock CPU fan in there.
CPU/APU is the AMD 6400K and motherboard is an MSI FM2-A75IA-E53.
I've currently go a gaping hole at the rear of the chassis where the PSU once sat, which I'm planning to cover with a wide mesh to stop anything metallic falling in. With the hole and with just the stock CPU fan running at 3200RPM it sits at about 42C idle and warms to about 50C+ when playing flash video, slightly cooler when watching HD video.
The stock cooler is a bit cheap and fairly audible, although it's a lot quieter now I'm running the solid state PSU.
I'd like a heatsink/fan combo that'll hopefully bring temps down by at least 5 degrees, maybe more, and be really quiet. I've got quite a lot of headroom in the case above the stock cooler due to having removed the PSU. See my hasty MS paint diagram
The RAM only gives about 10mm clearance on the stock cooler but once you get about 8mm above the stock cooler height of 40mm it's a wide open space.
Any suggestions as to which cooler to buy? It would be a bonus to be able to project the heat out to the rear hole/grill and also draw warm air from the motherboard.