If you want very low voltage RAM, this G.Skill ECO Series with pretty much the same speed & timings is the way to go at $103.
There are a couple of kits that are $2-3 cheaper than the Mushkin, but they're 1333 MHz. Unless you're really trying to save every $ possible, you might as well get the 1600 MHz Mushkin kit as opposed to the couple of cheaper 1333 MHz kits.
When Your Only Running A 23" Yes, When You Consider CUDA And PhysX....... Again, Yes
You're probably going to get more raw fps with a 5970 in most games...but you're not going to be able to see the difference vs. the GTX 480, since 60 fps is pretty much the limit of what the human eye can see.
CUDA doesn't do anything for gaming, so that's kind of moot.
I don't really think that PhysX is being used in that many games. Even in those it does, does it add a lot to gameplay? I don't know, since I haven't seen demos with/without, but it doesn't seem like it's a game-changing, must-have feature.
That being said, the GTX 480 is cheaper, and if you're just planning on a single-card/single-monitor setup, it may be a better choice than the 5970. If you're looking at eventually CrossFire-ing or going Eyefinity, the 480 isn't a great choice, as SLI & 3DVision aren't supported on that motherboard.
Honestly I would get a GTX 470 for cheap (less than 280$) and put that cash on either an IPS or 120hz monitor (will hold it's value MUCH better than the vidcard).
I would look into switching to a P55/i5-750 build for serious gaming or an eventual SLI. The 965 will be a bit of a bottleneck on either a 480 or 5970. Alternatively, look into a 1055t for futureproofing.
That AMD mobo you have listed is bad. For the same price a gigabyte 890 chipset mobo can be had with newer and nicer features, while for 50$ less an Asrock 870 extreme 3 will offer those features but only with x8/x8 PCIe links (not a huge loss at all, none at all if you're single GPU).
Ok so let me get this straight. I am getting SAMSUNG XL2370-1 monitor which has 1920X1080 resolution so thus will utilize the full potential of ATI 5970. To go with that I am thinking of getting Intel i5-750 since according to benchmarks has an edge in gaming as compared to AMD Phenom II X6 1055T Thuban. As for RAM I am thing of going for Mushkin Enhanced Blackline 4GB (2 x 2GB) DDR3, the G.Skill ECO Series looks ugly ;( What is the best motherboard using P55? Yes I might try SLI in future. Thanks.