Caporegime
Try a Selective Start-up and disable all non Microsoft items, temporarily, since maybe it is some other software on your system that is involved.Thanks for all the help guys, I will try this.
I am on latest bios and chipset drivers already, someone commented that maybe a dodgy PSU, It is a few years old now but has been rock solid- its a be quiet 1200W and nothing going on to suggest it's failing as once GPU drivers are reinstalled, the problem goes, and I can play for hours with no issues. I am one of those people who always likes to run windows update and CClean before I game and reboot.
Even deleting the %temp% folder before I start. I have also disabled TPM in the bios as after digging around heard about stuttering issues.
If that doesn't help, re-enable those items and look elsewhere for the issue.