BMW M4; S1000 RR
Watch a couple of Youtube videos and anyone can build a PC. Windows 10 licence can be had for around £21. The 8600K is a 6 core processor and clocks very well which will help with the high refresh rate monitor.
The CPU doesn't have much impact (if at all) on refresh rate dude.
i5 is the better VFM chip than an i7 (agreeing with you there). Always buy an i5 unless budget isn't the concern.