Advice on upgrade/rebuild on ~5yr olg gaming PC

[zeawyatt]

I built this gaming PC about 5+ years ago and since then have installed an SSD and replaced the GPU. Recently the computer is getting buggy and the performance is becoming an issue so I'm keen on a rebuild.
I was hoping to get advice on what if any components I should keep (if any), and what upgrades will give the most bang for the buck.
Budget ~$800usd

Current build:
CPU: i5-2500k
GPU: GTX 960 4GB
Motherboard: asustek p8z68-v pro
RAM: 2x DD3 4gb 1600mhz
SSD 840 EVO 500GB
2x 2TB Hard drives
1x 500GB Hard drive
Power: Not sure but I'll check requirements when build is finalised
Case: fractal arc midi
Monitor: old! Benq g2420HD

Any advice appreciated!

 

[vapour]

are you playing AAA titles? If not, I will reinstall OS first to see if it resolves issues.

 

[ArchitSahu]

^ If that does not work, you can keep your storage drives, monitor and case. Re confirm what is your PSU which can be re used.

Here:

Intel -
PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8400 2.8 GHz 6-Core Processor ($220.88 @ OutletPC)
Motherboard: MSI - B360-A PRO ATX LGA1151 Motherboard ($69.99 @ B&H)
Memory: G.Skill - Ripjaws V 16 GB (2 x 8 GB) DDR4-3000 Memory ($109.99 @ Newegg)
Video Card: EVGA - GeForce GTX 1070 8 GB SC2 Gaming iCX Video Card ($339.99 @ Newegg)
Total: $740.85
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-11-08 20:46 EST-0500

Ryzen -
PCPartPicker part list / Price breakdown by merchant

CPU: AMD - Ryzen 5 2600X 3.6 GHz 6-Core Processor ($209.99 @ B&H)
Motherboard: Asus - TUF X470-PLUS GAMING ATX AM4 Motherboard ($115.99 @ Newegg)
Memory: G.Skill - Ripjaws V 16 GB (2 x 8 GB) DDR4-3000 Memory ($109.99 @ Newegg)
Video Card: EVGA - GeForce GTX 1070 8 GB SC2 Gaming iCX Video Card ($339.99 @ Newegg)
Total: $775.96
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-11-08 20:49 EST-0500