I'm not saying that you NEED to take my opinion. I've made up my mind about you: you like Seasonic, and Intel, and Velociraptors. There's nothing wrong about that. I just think there are ways to get better performance for your money.
You definitely disagree. And you know what? There's nothing wrong with that. I don't tie my pride and worth as a person on whether people follow my advice. Is it somewhat upsetting when people don't take it, perferring a different route? A little. But I get over it.
I probably seem obsessed with numbers, metrics, and stats above subjective feelings. That's because people get tied to their decisions, particularly product choices. We the first world, after all, are a consumer culture. People often make irrational choices, but numbers don't lie. I feel a little personal shame at my own build because it simply isn't very price efficient: there's lots of money put into the case and PSU that could have gone into a superior GPU, monitor, or simply saved. But I understand (even though I often forget!) that that's not the end-all-be-all of life.
I mean, you'll get a working computer either way. We don't have to fight about it. I think I need to take some steps back from what's happening, since I seem to have made you angry at me.
I'll try to fit a few recommendations within what you want.
This Intel Z75 mATX motherboard is a bit cheaper than the one you chose. Since HDDs can't fill up SATA 3Gb/s, you'll be fine for up to six Velociraptors in RAID.
You can get Seasonic made PSUs for a bit less if you accept them from another brand. Seasonic makes it, the other company sells and decorates it. An
Antec Earthwatts at 500W is enough for any single GPU, and costs only $68.51 before shipping.
Finally, please consider getting 7200RPM drives in RAID10. You can get nearly the speed and much more security and space for roughly the same price. It's even still got the "cool" factor of RAID (two kinds at once, no less).
I'm honestly and sincerely sorry if I upset you. If you'd like, I'll stop posting in this thread.