Is DDR3 1600 CAS 9 enough? Should I spend £30 extra on CAS 7?

Tradesman1

Legenda in Aeternum
The 1600/9 should suffice, however if you want better performance at a better price might check out options of 1866/9 or or 1866/8 sets of DRAM, they may well cost less than the premium 1600/7 sets and for instance 1866/8 can be run at 1600/7 or 1866/9 at 1600/8