100 fps difference between gaming setups

Feb 3, 2018
5
0
510
Hello, i have a little problem, can you help me.
My main pc setup:
cpu: i7 5820k
gpu: rx 570
mobo: asus x99 deluxe
ram: ddr4 16 gb 3000 mhz 4x4 quad chanell
ssd: Patriot 120 gb
win 10

I just build gaming setup for my bro:
cpu: i7 3960x
gpu: rx 570 (same gpu)
mobo: msi x79a-gd45 8d
ram: ddr3 32 gb 1866 mhz 4x8 quad chanell
ssd: Patriot 120 gb (same)
win 10

And here is the problem, i run cs:go on my main pc, it shows average 250 fps. But when i run on my second new setup, it shows only 150 fps. So, who's causing bottleneck? Any ideas, thank you !