PC Upgrade Advice

I am looking at upgrading my PC so that I can play the latest games, currently I use my computer for many applications from Graphic editing, CAD etc. My current specs are:
Gigabyte MB Z87X-UD4H
Intel i7 4770K
16GB DDR3 Ram
NVidia GeForce GTX 660Ti (Gigabyte)
Asus Sound Card Xonar D2
500 GB SSD Samsung 850 Evo (Boot Drive)
2 x 1TB Western Digital Black Hard Drives
Corsair 750 PSU
Windows 10 Pro 64 bit.

Please can anyone give me a little advice as to what they think would be the best upgrade path, or would I be best starting from scratch and building a new system.
Any advice would be gratefully appreciated.

What sort of budget do you have for this.

I have similar CPU, and RAM. Recently upgraded to the Asus ROG Strix 1080 and can now play all the latest games on Ultra at 1920x1080 without a problem

up to £1300 for this Upgrade or complete system.

TO be honest, I would do the GPU first as that’s an easy replacement. Run with that first and see how you get on. If you are finding some applications are still lacking cause they are CPU intensive then you can consider replacing the CPU,MB,RAM with latest tech but no point doing that unless you really need to, so would start with GPU.

You will see a massive boost in performance alone going from 600 series card to one of the 1000 series cards.

Agree with both comments here, not much to be gained from changing out the cpu and ram, so a shiny new 1080 would be best option and well with in your budget.

Many thanks for you help.