Thanks, jeffinsf, that information is very useful! It sounds like I'll be underclocking/undervolting to get the CPU to run fanless at a reasonable temperature. It's a HTPC, though, so anything goes as long as it doesn't skip.

I'm in the same place as you, but I've already purchased a SI-120 and 2 yate loons. I can't speak from firsthand experience, but it seems that with at least all (decent) s939matx boards, fin orientation DOES work well. The fins of the SI 120 run parallel to the 2 s939 mounting screws. After creatin...

I'm planning on buying an NSK2400 for my HTPC, but I'm worried about heatsinks. I want to go fanless on the CPU, letting the case's exhaust fans do the work. I'm considering the SI-120, XP-90, and XP-120. What I'm worried about is the fin orientation. To go without a CPU fan, it seems like I need to...