That build will work, but there are HD 6850 or HD 6870 cards at the same price that will perform much better.
You might also want to consider an Intel system. By getting a cheaper case and moving down to 8 GB of RAM, you can get an i5-2400, which will perform much better in most situations, particularly gaming . Unless you have specific editing or rendering needs, you won't miss the extra RAM.
The reason I post that specific review is because the 6790 is quite a bit worse than the 6870, but the 6790 beats the 550 Ti pretty much in everything. So with that said it'd give you a good idea where the 550 Ti places with the 6870. The 550 Ti is a little better than the 6770/5770 so here's the 5770 vs 6870 to give you an idea. http://www.anandtech.com/bench/Product/296?vs=290
Thanks for the replys,
Ya i might do a bit of 3d animation and sort on Autodesk 3DS max, but other than that it will be a gaming computer. My budget in all is $850. Also i am going to use this case, no questions asked
Haha no worries, well I haven't used this build but from what others tell the motherboard is good, if not great. The chip is amazing for the price, better than most AMD chips of similar price, and the 6870 is a great card. As for the PSU it's a great PSU and reviews have been pretty decent for it.
If you've got $850, there should be an i5-2500k in there. You can easily overclock it to 4.4 GHz for about a 40% speed increase.
Since you're set on that gigantic case, I got a full ATX board, with heatsinks on the VRM and an 8-pin power connector. Compared to a budget mATX H61 board, this one can overclock, should run cooler and be more stable, has more RAM slots in case you want to add memory, and has another PCI-E slot if you want to Crossfire later.
RAM: G.Skill or bust.
I chose that PSU because I was having trouble finding something with cables that would span that gigantic case of yours from a bottom-mounted position. I actually use this exact PSU, so I took the side panel off my computer and checked to make sure the motherboard power cable would be long enough.
With shipping, I think it comes out to $855. There's also $25 in mail-in rebates.