So I've been out from the computer things for a while so please give me some hints.
I am trying to find a reasonable trade-off between HTPC AND MUSIC STUDIO PC for digital piano. No need for gaming. I will place the HTPC quite close to the tv and listening position so that's why quiet.
-S/PDIF coaxial or optical for Dolby Digital 5.1 or DTS sound, no need for HD sounds or whatever 7.1
-Enough power to play 720p and 1080p stuff (processor and/or graphics card)
-Enough memory (I guess 2GB of 800Mhz would do it or do I need more)
-Silent (power supply, CPU cooler, graphics card)
-7200 rpm hard drive
Nice to have:
-Some good quality low latency ASIO soundcard with USB midi input (???)
So I am looking for:
Case (ATX or mATX?)
Power supply (silent and enough of Wats)
Motherboard (there are tons of them)
Graphics Card OR integrated if can be found
CPU with silent cooler
You don't say what OS you want to use so I assume you plan to use Win7. Keep in mind that windows media center doesn't come with every version of win7. The other software you should consider installing is XBMC and Boxee. A new version of XBMC was just released and it's sweet (there are at least 7 high-quality skins), and a new version of Boxee is going to be released the 2nd week of January, which most people will like if they enjoy controlling their HTPC with a remote.
Some things to keep in mind:
o If you were building both backend and frontend computers, and keeping the backend in the basement, then 7200 rpm hdds are the way to go because they work better in RAID and their clatter is not a problem. But since you plan on sticking the computer next to your TV then I would seriously consider 5400 rpm drives since they give you nearly the same performance but are much quieter. I like the WD green drives for this, but keep in mind that green drives don't work well in raid. WD appear to be the most reliable.
o You can find mini-ITX boards that have nearly all the features of yesterday's ATX boards. Get a full-size board only if you actually need all the slots. Micro-ATX seem to be the best compromise between size and features and they are more economical, generate less heat, and save space. Girlfriends prefer smaller, so that should be taken into consideration.
o If you want to use integrated graphics then Nvidia's 9300 and 9400 and ION chipsets are powerful enough to do High-Def. They aren't powerful enough for high-end gaming, but you say that's not your priority. These chipsets are also powerful enough to do Flash once Adobe releases their next Flash player.
o If you don't want to buy a sound card then you can still get very good sound if the motherboard has something like an ALC888 or ALC889 chip. I believe the nvidia 9300/9400 also has good sound and can generate 7.1 channel lpcm over HDMI.
o Keep in mind that Adobe Flash is becoming more and more important in an HTPC. Right now Flash is usually decoded in software by the CPU which means it puts a major strain on weak processors. Adobe is going to correct this shortly with their upcoming 10.1 release of their Flash Player; Flash will then be handled by the GPU instead of the CPU. This will make youtube much smoother. Nvidia chips appear to work better with the Adobe codec. I would avoid the nvidia gt 210, but the gt220 or anything higher would be able to handle flash well.
o Don't forget your remote. And, just as important, make sure the remote comes with a receiver that is plugged into the computer. There are 10,000 different remotes to choose from. I think most people just pick up an infrared windows media center remote that runs around $25.
o You'll save a few bucks if you go with an AMD cpu. For example, even an AMD Athlon II X2 245 is sufficient for an HTPC and it's only $62. It also runs cool, which means the fan can run slow. If you go AMD make sure the motherboard supports Cool'n'Quiet and you'll save a few bucks in electric bills.
o The AMD 785g chipset is suffiently powerful enough to handle High-Def video. It's integrated audio is only 2-channel but for 95% of people that is fine. The audio can be decoded as Dolby Digital and DTS 5.1 by an A/V receiver. [One caveat: you'll have fewer problems if you stay away from AMD graphic chipsets if you decide to use Linux.]
If you go Intel, something like an Intel Pentium E5300 2.6GHz is going to cost a few extra bucks. This chip also runs cool and is sufficiently powerful as long as you pick a decent video card or IGP.
o Some people swear you need 4 cores for an HTPC, but unless you plan on doing a bunch of video encoding it's really not that important. If you pick a decent video card then almost all the work will not even be done by the CPU but will be done by the GPU, especially after Adobe fixes their flash player.
Here's one suggestion for a video card: http://www.fudzilla.com/content/view/15941/1/
It's low-profile, has HDMI, and doesn't have a fan. I don't think you'll find it on store shelves for a week or two, however. It's new. It's going to run about $70.
o You don't have to be real picky with your memory choice as long as you are not going to overclock. If you pick a name-brand DIMM and a name-brand motherboard and the pin counts match then you should be fine. If you are concerned about slow memory, look for memory with a CAS of 5 or lower, and 800 Mhz or higher. Memory with a CAS of 5 appears to be the sweet spot between price and performance.
o More important than choosing a silent cpu cooler is making sure the motherboard has a 4-pin fan connector and the BIOS supports fan control. Those items can be checked by reading the motherboard manual. Make sure that you don't get carried away and buy a CPU that runs hot is also a good way to control fan noise.
o For an HTPC, also make sure the BIOS supports wake-on-usb. Not all motherboards do.
o If you decide to go with a small case then don't forget to go with low-profile cards. You'll get better air flow and your case wont bake.
o You should also probably look for a motherboard that has an eSATA port, just in case you need it in the future.
o The case fans that come with cases may need to be replaced if it is too loud. You can get a quiet one for $2 from newegg but the shipping cost may be excessive. Also make sure your BIOS supports fan control for the case fan.
Sorry, I'm not going to get into recommending too many specific components since there are so many choices. But the link at the top of this post does make recommendations.
Video Card: ATI Radeon 5450 (Cheap, Passive Cooling, Enough for HD video but not gaming)
CPU: Intel Core i3(Low power consumption)
Memory: 2 or 3 GB DDR3
Motherboard: GIGABYTE GA-P55M-UD2(Power saving features are great, small, more than enough outputs)
PSU: Any PSU 450W or better will do. Depends on what you want to spend. More efficient units come with a hefty price tag. Something like this will do just fine for cheap.