That's some slow ass RAM^^^ Get this http://www.amazon.co.uk/HyperX-FURY-1866MHz-Memory-Module/dp/B00J8E90I2/ref=sr_1_1?ie=UTF8&qid=1441052344&sr=8-1&keywords=2X4GB+RAM free delivery aswell
I'd say going to a 970 or R9 390 would be a better option as the difference is massive. But if you don't want to spend £250 then keeping your GTX 660 imo is better