System build - critique

Performancewise, you would be better getting 4x4gb or 2x4gb & 2x2gb of ram instead of three sticks of 4gb, since they wont run in dual channel mode unless you have a even number...

Yes, it completely went over my head. Sorry.
I will be getting the 2x4gb to form 8gb. I may even just jump to 16gb although I know it is overkill.

Try one of these two for OC'ing:

COOLER MASTER Hyper 212 EVO RR-212E-20PK-R2 Continuous Direct Contact 120mm Sleeve CPU Cooler Compatible with latest Intel 1366/1155 and AMD FM1/AM3+ $44.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

COOLER MASTER Hyper 212 Plus RR-B10-212P-G1 "Heatpipe Direct Contact" Long Life Sleeve 120mm CPU Cooler Compatible Intel Core i5 & Intel Core i7 $29.99
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

My 212 EVO keeps temperatures reasonable at 4,5ghz no problem, results may wary though.
Depending what cooler you end up getting, you might want to consider getting the low profile version of the vengeance ram (especially if you want to fit 4 sticks, on my Asrock E3 G3 tall ram would be quite the squeeze in the first ram slot) And please do get an even number of ram sticks!
A gold rated 850w powersupply is overkill for any single GPU, and you might have low efficiency as that GPU idles quite low.

Few things:

- As far as cooling goes, one really good option to try, especially if you're worried about RAM clearance or noise, is the Zalman 9500, which is probably one of the most underrated air cooling units out there. Zalman really knows how to make CPU coolers; only problem is that most of them are just so amazingly huge that who knows if they'll fit in your case. This one will. CoolerMaster really only has the 212 series that they luckily nailed the ball out of the park on, but the rest of theirs are just big honkers that try to get by on size and airflow volume like everyone else. I'd take the same sized Zalman cooler over an CM cooler any day. Newegg also happens to be having a huge sale this weekend that includes the 9500, so I'd look at that:
http://promotions.newegg.com/NEemail/Feb-0-2012/Preside...
www.newegg.com/Product/Product.aspx?Item=N82E1683511800...

- You do not need an 850W power supply. Main thing is to check that your power supply has two PCIe 6-pin connectors to run your card, and then 500W-600W will do fine. Whaddya know, one of those is in the same Newegg sale for $40. www.newegg.com/Product/Product.aspx?Item=N82E1681734101...

People make a big deal about the quality of the manufacturer on power supplies, and rightfully so. This is the #1 area where you need to choose blindly between a Chinese knockoff that's a piece of crap, or a Chinese knockoff that does OK. Basically every power supply out there is a Chinese knockoff, and it's hard to tell what's what. This article, should you find it interesting enough to read, will tell you what's going no with that:
http://www.tomshardware.com/reviews/power-supply-oem-ma...

go to "N-R" for OCZ and "S-T' for Silverstone's real manufacturers. Basically, you'll find that they use some of the same manufacturers who are both OK (FSP, Sirtec, Impervio), OCZ uses one who is known for best quality (ChannelWell), and Silverstone throws in a few random unknown brands. But Silverstone charges double the price. I'd definitely go with OCZ in this case.

- You should reconsider whether you need a $400-$500 video card. In my experience, if you spend about $200 on a video card, you will be able to enjoy your games fully, and nobody except a hardware geek will be able to tell the difference between your GPU's performance and that of a GPU that's double the price. Your $200 video card will be good for several years, and toward the middle-to-tail end of that, indistinguishable from the premium GPU. Right now, that would mean you'd be looking at about an HD6950.

It all depends, man.

Most PSU brands have good quality aswell as bad, most manufacturers make both good and bad. Seasonic (manufacturer and brand) aparently refuse to make PSU's below a certain quality, and all the current Corsair PSU's are at least decend aswell.
Here is a Review database: http://www.overclock.net/t/738097/psu-review-database
And here an approximate list of quality: http://www.eggxpert.com/forums/thread/323050.aspx