If computer freezes and then a reboot solves the problem it seems more software than hardware problem.
Check for viruses, malware.
If you have WIN 10 run the Systems Diagnostic Report, check the Event log.
Do you run a spesific program when this happens? Did you install a new application or an update before this problem occurred?
Sorry for delay in reply, thanks for help given so far.
The problem seems to have started after the latest Windows 10 update to ver 1909. I could role it back but that might store up future problems. The freeze-up is completely random, no pattern to the programs in use at the time Im told (this is my daughters PC)
So far I've updated all the drivers, reset the swap file and checked the programs running at startup.
These are the system specs
Windows 10 Pro 64-bit
CPU Intel Core i5 4670K @ 3.40GHz 29 °C
Haswell 22nm Technology
RAM 8.00GB Dual-Channel DDR3 @ 799MHz (9-9-9-24)
Motherboard Gigabyte Technology Co. Ltd. Z87-HD3 (SOCKET 0) 21 °C