Don't get a 660ti, get a 7870 instead. The 660ti is in general stronger but price per performance the 7870 is way better. I would honestly pick a 660 over the 660ti. Some people at tomshardware were able to over clock it to be is strong as a 660ti. You would also be better off going with an fx 4170 if this is a gaming rig or a phenomiix4 975 or 980 http://www.tomshardware.com/reviews/gaming-cpu-review-o...
If this is for gaming get 8gb instead of 16gb.
"As it stands, AMD’s position correctly reflects their performance; the GTX 660 Ti is a solid and relatively consistent 10-15% faster than the 7870, while the 7950 is anywhere between a bit faster to a bit slower depending on what benchmarks you favor. Of course when talking about the 7950 the “anything but equal” maxim still applies here, if not more so than with the GTX 670. The GTX 660 Ti is anywhere 50% ahead of the 7950 and 25% behind it, and everywhere in between.Coupled with the tight pricing between all of these cards, this makes it very hard to make any kind of meaningful recommendation here for potential buyers. Compared to the 7870 the GTX 660 Ti is a solid buy if you can spare the extra $20, though it’s not going to be a massive difference. The performance difference is going to be just enough that AMD is going to need to trim prices a bit more to secure the 7870’s position." http://www.anandtech.com/show/6159/the-geforce-gtx-660-...
Price per performance the 660ti is worse than the 7870 currently. Yes The 660ti usually beets as I stated, but the 660ti is on average 30-40 more than the 7870 and it is not that much better, and the 7870 also beats very often and in the near future that difference will be negligible. Also the people at tom's WERE able to get it to perform better than 660ti in 4 or 5/10 benchmarks with overclocking
what games are you playing on it? and how are they performing? im thinking of updating my vid card to a 660 (currently have a 560) also but wondering what the gaming performance will be with a fx 6100 to pair