Those graphics cards will be weak; they're the 192bit versions of now 3-generations old tech. Everything else looks pretty extreme to me. I don't know how much data you'll be storing; I don't have all that much, and have a pair of 2TB drives in RAID1. Three drives makes me think you have in mind a RAID5, which can be a lot of trouble; the WD Black drives are fast, but I don't think they have TLER, necessary to keep that level of RAID from dropping members that encounter errors.
For the graphics card, I'd look into a pair of HD7870s at the least, and HD7970s would be more in line with the rest of the rig.
If you're not going to overclock, you can get a non-K CPU to lower the cost a little; may not be worth it if you might want to overclock later.
I could see adding a couple of fans, but five seems like a lot, especially in a non-overclocked (and therefor cooler) rig.
Edit: Check to make sure about support for nVidia Surround vs. AMD Eyefinity. If you choose nVidia, GTX760s or GTX770s would be good; get at least 3GB/card, preferably 4GB for multiple monitors.