Possible upgrades to old pc

[markomania]

I've had my PC since 2013, upgraded a few bits over the years and it's been relatively ok.

Since getting back into gaming recently I realise it's struggling quite a lot to keep up. I'd imagine it's mainly cpu related as I haven't touched that since I built it other than an overclock.

It's only cs2 and a bit of gta5 that I'm playing currently so I was wondering if there was anything that would help or is it too old to improve now?

CoolerMaster CM Storm Trooper Full Tower Gaming Windowed Case
Intel 3rd Generation Core i5-3570K CPU
Gigabyte GA-Z77X-D3H LGA1155 ATX Motherboard
HyperX FURY Series 16GB (2x 8GB) DDR3 1866MHz CL10 DIMM Memory Module Kit - White
4GB Gigabyte GTX 970 G1 GAMING
EVGA Super NOVA 850W G2
Samsung 860 EVO 1 TB SATA 2.5 Inch Internal Solid State Drive

 

[markomania]

I haven't really thought about budget, just wondering about options atm, I'm completely out the loop with hardware.

My monitors are Full HD (1080p) 1920 x 1080 at 75 Hz. I have 3 but only use 1 when gaming.

I suppose I should really look at doing a full upgrade to future proof rather than throw money at my current pc. I was hoping someone said just buy this 1 thing and it'll be perfect for another 3 years