"a i7 few core"? Not fully understand, I assume you mean do we need i7 if only gaming.

Well, it depends on your budget, if budget allows, surely the i7 is more future proof, we have seen quite a few latest titles are using the extra threads of i7 already, for example Fallout 4 and the currently most CPU demanding single player game, AC: Syndicate.

I tested AC: Syndicate on i5 4460 and i7 6700K, it turned out that i5 is somehow suffering from CPU bottleneck, CPU usage is constantly 90% and above for all cores, sometimes it even hit 100% for all cores, this causes issues like mouse lag/delay. This could be a poor optimization from Ubisoft (they are well known for poor PC port afterall  ), but rest assured, open world games tend to draw more CPU power compared to other genre games.

If you are more towards this type of games, get an i7 is highly encouraged.

Your budget can fit i5 + GTX960/R9 380 at most, running max graphics settings with this GPU with mostly yield < 60 FPS, medium/high settings is more FPS friendly, of course they can run max/ultra settings, but you might face unstable FPS and screen tearing.

Intel Core i5 6500 - RM 876
MSI B150M Bazooka D4 - RM 399
Corsair 8GB DDR4 2133MHz Value RAM - RM 200
Zotac GTX960 2GB GDDR5 ZT-90306-10M - RM 840
WD Blue 1TB HDD - RM 225
Seasonic M12II EVO 520W - RM 349
Bitfenix NOVA - RM 149

Total: RM 3038 (Techview price inclusive of GST)