For me, the processor speed for the PVR doesn’t need to be that high. Between the hardware MPEG2 encoders and the relatively low CPU loads of playing video, there just isn’t a need for a fast processor. And slower processors usually give off less heat, which means they can be kept at a safe temperature with less cooling. That means a slower and/or weaker fan, which means a quieter box. For something sitting next to my TV, that’s the most important part. Now, if you want your HTPC to do processor-intensive HDTV-resolution scaling, or want to play the latest games on it, you’d probably want to step up to a more powerful processor. At that point keeping the processor cool becomes more complicated.
Lots of posts in forums recommended AMD processors instead of Intel, because they tended to run cooler. I wound up getting an AMD Sempron 3000+ (1.8GHz). This is the slowest processor that uses AMD’s “Cool’n'Quiet” technology, which will let the processor run at a slower speed if there’s not much work for it to do. Most of the time this should let the processor run stepped-down, making it even easier to keep it cool.
The one I ordered is the 90nm version, which runs cooler than the older process.
For a motherboard I went with the Asus K8N. The key features that I wanted were:
- On-board digital audio output, preferably coax. I don’t want to add in a sound card, and I definitely want to use a digital connection between the computer and my receiver.
- Supports Cool’n'Quiet. No point getting a processor that does if the motherboard doesn’t.
- Can adjust the processor’s fan speed based on temperature. You need this for the “quiet” part of Cool’n'Quiet to work.
- Enough PCI slots. This motherboard has 5. I figure I need at least three (2 encoder/tuner cards and one wireless card), but would hate to not have extra slots available just in case.
I read mixed things about the stock AMD cooling fan; some people said it was quiet enough, others said it wasn’t. I decided to get the retail processor box that came with the AMD heatsink and cooling fan, and it’s definitely quiet enough for me so far. I haven’t yet put the motherboard in the case, so it’s just sitting on a box. In the case everything might get warmer, and the fan might have to run faster, and so it might become audible. Right now, though, it’s completely silent.