Bottleneck101 :
i bought a r9 290 and have a athlon x4 860k and a i5 3330s from my brothers old dell. What would least bottle neck my system and preform best. (also overclocking 860k to 4.5ghz)
So I'd recommend checking out this thread
Here
It shows comparisons of the 750k and the 3320 as far as GPU scaling goes. They aren't your identical chips, but they are the two lesser counterparts of them. It shows that on the 290 the performance difference is not extremely high, and actually within the margin of error at about .2 of their index.
On that note, check out these results I got from GPU boss
Here
Looking at those results, It shows that the 3330S got again marginally better performance in simulated benchmarks.
So looking at these findings, all I can give you is that the 860k is newer, and if you plan on selling the one you don't use the 3330s will give you a full $50 more and wont give you much of a performance hit. So if your goal is to sell one, I recommend using the x860k. (I got the $50 by looking at these two posts on eBay one with units sold the other with watchers, Links:
860k,
3330s)
Hope this helps!
Regards,
Signal