Upgrade Advice for Gaming Computer

[M Nags]

Hey all, bought this gaming rig 4 years ago, it's served me very well and I can't complain but I have money to spare and wanted to ask the community where I should upgrade (or if theres no point) to get the best improvement.

Specs are as follows:

CPU: Intel Core i7 4770K Haswell 3.5GHz 8MB
CPU Cooler: Corsair Hydro Series H100i CPU Cooler
Motherboard: ASRock Z87E-ITX LGA1150 mITX Motherboard
Memory: G.Skill 8GB Kit (2x4GB) DDR3 Ripjaws X C9 1600MHz
OS Drive: Samsung 840 EVO Series 250GB SSD
Storage: Drive Western Digital Blue 1TB
Graphics Card: eVGA GeForce GTX780Ti
Case: BitFenix Prodigy Black mITX Gaming Case
Power Supply: Antec TruePower Classic 650W Power Supply
Monitor: BenQ RL2455HM 24inch

I'm not so much having issues with my current build, I just want to see if I can notably upgrade.

Thanks

 

[faalin]

CPU is strong enough, GPU is what I would upgrade and then maybe a new kit of ram to 16GB