I want to build a htpc using an Amd 4400 65 watt processor. So silence is the key. I a looking for a fanless heatsink solution. Can anyone recommend a good heatsink?

What case are you looking at using?

Yeah, you need to let people which HTPC case you are using and also it's dimensions.

If the case is 5" tall then I would probably recommend the Scythe Mini Ninja which is 4.53" or 115mm tall. This is probably the biggest heatsink I would suggest for a 5" tall case 'cause you gotta remember that the motherboard will be sitting on top of spacers.

Scythe SCMNJ-1000 80mm Sleeve "NINJA MINI" CPU Cooler

This is the case I am looking at it has a an 80m case fan and it also has a fan on the power supply which I would also like to replace.

http://www.newegg.com/Product/Prod [...] 6811154087

You might want to consider the Scythe Shuriken. It's made for half-height cases and it comes with a PWM controlled fan: