Combination HTPC and NAS
I think it's always better when you split them up. But you can do it. It should work fine.
GIGABYTE GA-Z77X-UD4H LGA 1155 Intel Z77 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard with UEFI BIOS
That board is expensive but I am not sure you need any of the reason why it costs more. I'd opt for an Asus with Intel Lan for the same price (high end) or an Asrock Z77 for $60 cheaper. I like both better. But that board should work.
Does it have HDMI ? That's really all you need. HDMI + Intel Lan + USB3.0 are the three important things. You can add intel NIC card later... if you need great network performance.
Do you realize why that board is $60 more ???
I am not sure you need 3 x16 slots for triple video cards. one x16 or two x16 slots would be enough on a cheaper board in case you wanted to upgrade or add a GPU. It's unlikely you'd have more than 1 GPU card if at all.
Save your $50 and look at an Asrock Z77 3 or 4 level for $89-$109.Intel Core i3-3225 Ivy Bridge 3.3GHz LGA 1155 55W Dual-Core Desktop Processor Intel HD Graphics 4000 BX80637I33225
Very nice CPU but you can get i5 3570k for about the same price ($205 total with Asrock motherboard) with the Microcenter bundle deal if you have one near you. $169 for i5 plus you get $40 off a motherboard.
SAMSUNG 840 Series MZ-7TD120BW 2.5" 120GB SATA III Internal Solid State Drive (SSD)
Very nice SSD. Best 3 SSD's are SAMSUNG840, Plextor M5 and Vertex4 IMO. Those are mainstream normal good choices
On high end the big brothers are SAMSUNG840PRO (pro has better nand inside and faster speeds) The Plextor M5 PRO, and the OCZ Vector.
You'll do well with that SSD.
G.SKILL Ripjaws X Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-4GBXL
Spend $12 and get 8GB. Get 1866mhz too.SILVERSTONE Black Aluminum / Steel Grandia Series SST-GD08B ATX Media Center / HTPC Case
Freakin' really nice case. Well done.
Western Digital WD Green WD20EZRX 2TB IntelliPower 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive -Bare Drive
$89.99 x 4 = $359.96
You can get RED for the same price right now. Longer warranty. No head parking issues if you ran Raid 5 (you mentioned earlier)
You can not run any hardware RAID with green drives they have TLER issues.
SeaSonic X series SS-400FL Active PFC F3 400W ATX12V Fanless 80 PLUS Platinum Certified Modular Active PFC Power Supply
Expensive but very nice. A fan Rosewill platinum or 80% gold is near silent for half price though. As is a Seasonic Variant with a fan like Antec Neo. You might want the fan with that many HDD's inside a HTPC case.
JRemote via iPad, iPhones
(JRiver remote solution for Surface Pro pending)
Jriver is a good player but a poor front end. Do you plan to use mediabrowser?
MS SyncToy for sync / backup (unless a RAID solution is better and I can figure out how to set it up)
I'd look into Flexraid. It has drive pooling and parity backup. Combine $10 a month crashplan and you can back up all 8TB to the cloud and rebuild any single failed drive locally with flexraid software raid and it's parity based backup.
Software Raid > Hardware raid. Raid 5 is basically software raid. I'm confused if you want to run hardware or software raid. Raid 5 is not really much different than flexraid. Flexraid allows you to read the contents of your drives on any machine. You don't need a raid controller, and you can rebuild a failed drive from the parity backup. You can add or subtract both full or empty drives from your storage pool.
How much storage do you need? 8TB ?