He likes a load of CPU heavy games so I have to use an i5 4440, paired with which £100 ish pound GPU? I think skyrim, civ 5 and MMO games are his ideal type. WIll Nvidia be better at these?
The 650 Ti was a great card in that price range but the 660 tends to be a little pricey especially on your side of the pond. The 660 and 270x are well above £100 on most UK sites tho.
Here's a comparison of the two cards. I would think the R9-270X would outperform the GTX 660. Since the R9-270X is basically a re-badged HD 7870 (I had both the 660 and 7870), the R9-270X should be faster. http://www.anandtech.com/bench/product/1043?vs=1039
When I had both cards, the HD 7870 OC would always out perform my GTX 660 OC card. Both as a single card and in CF/SLI.
The 650 Ti was a great card in that price range but the 660 tends to be a little pricey especially on your side of the pond. The 660 and 270x are well above £100 on most UK sites tho.