Update:
My PC had been running normally and was very happy for about a week. I had XMP enabled, but nothing else changed in BIOS - completely default.
It's just started to crash again and I have absolutely no idea why. It sometimes happens straight after booting up and logging into my windows account! So it can't be temperature related.
Sometimes it happens when simply watching a Youtube video with nothing open in the background, sometimes when gaming, sometimes when idle even!
Is there a way I can create a log file for why the PC has crashed?
Edit: It literally just crashed as I was typing that
I might be ready to throw this thing out the window.
are you trying for a cpu all core clock of 5ghz with 4000mhz ram?, tbh you'll be very very lucky to get that on both components, i suspect if you are overclocking both cpu to 5ghz and ram to 4ghz the imc on the cpu cant keep up, try your cpu clock only and if that holds increase your ram speed start at 3600mhz and boost to 3800mhz if the last setting works, if 3800mhz on ram works with a 5ghz all core cpu clock try 4ghz for the ram, if at this point you get any weird behavoir or crashes i do belive the ram is simply set to high for the imc on the cpu to keep up and no matter how many volts you use nothing will change, if you keep pushing you could damage the cpu so be careful