Well it depends on a lot of things, for example, X9SCM is a great server mobo, but has a very old built in GPU (i think a novex that doesnt even support 1080p, dont quote me on that but i think its right), so you will need a dedicated gpu, now mobo only comes with 4x 8xPCi (i think 2 are 8x and 2 are 4x), so no 16x pcie for a dedicate gpu, im not sure what gpu can you buy there that con work, i bet there are alternatives but none comes to my mind. Second issues is the OS, im not sure what you will be running, in a windows environment most gpus have drivers etc, but in some even linux some gpu have problems... so really comes down what OS you will use, and probably a maybe another mobo that has 16x pcie. Im just throwing some of my concerns doesn't mean im right, just for you to research, before you commit.
A dedicated file server can be running any other OS, while your htpc can run for example windows or whatever you like that can run whatever you prefer for your playback. But you can always build your server around the OS and mobo that you prefer and have your all in one, i just dont see certain OS/mobo combos doing it.
You're right, so I've changed my combo:
* ASUS P8C WS ATX Server Motherboard LGA 1155 Intel C216 DDR3 1600 -> with 2 x PCI Express 3.0 x16 + 2 x PCI Express 2.0 x16 so I could attach a nice nvidia graphics card if needed:http://www.newegg.com/Product/Product.a ... alParent=1
* Intel Xeon E3 1200 Family processor with NO graphics (there are also some "L" models with much less power consumption) -> http://ark.intel.com/products/series/53495
Im not sure either, its more widely available the buffered, even when i was researching my server setup, there were bigger modules available and cheaper than the unbuffered, but this is how the X9SCM is design, so stick to what have work for others.
There's no much info around about practical analysis with real results and comparison between different ECC types, but for what I've read, registered (buffered) ECC is the recommended choice when looking for stable environments and bits correction (sacrifying speed and dollars). Anyway, buffered ECC memory will require a server MoBo so I'll keep looking to find out if it worth the effort...
I had two MBs SUPERMICRO MBD-X9SCM-F, both died after several months. Now I will buy asus P8B-M, same chipset, but it has x16 pcie.
PS: some ati 5450 http://www.hisdigital.com/un/product2-508.shtml
are 1x pcie, so it fit into supermicro.
Thanks for your comment, I changed my mind. That Supermicro mobo was almost incompatible with the allinone system that I'm talking about.