Questionable performance on a decently powerful build

[Stonemask5]

I recently have upgraded my PC, swapping out my AMD A10-5800k for a i5-6600k. Since the chipsets are different, I also replaced my motherboard and ram. In most games, I have been getting quite poor performance, especially for my build.
Specs:
i5-6600k at 4.5ghz
Strix Gtx 970
MSI Gaming M3
1 8gb stick of Hyperx Fury 2133mhz
600w Psu
Personally, I think the issue is my ram (or lack thereof) and have ordered another 8gb stick. My friend thinks the issue is that I didn't reinstall windows to remove leftover drivers and other potential issues. Any clue one this?

 

[Zerk2012]

always do a fresh install of windows after a major upgrade like that.