Dead PC, move W10 to new PC?

Thanks for the above and assistance.

Good news here. I was just about to pull down the old rig but thought I would just try one more time to fire it up. Opened the case and poked and pushed everything again. I have already removed replaced all components and wiring and feel I know this old machine backwards, forwards and inside out. An old friend..

Well I was blown away.. BIOS beeps.. Hooray... Short lived as it froze shorty after grabbing the OS licence key...

Rebooted a number of times and just about to rip it apart and beeps! BIOS couldn't find the OS! Sorted and now it is up and seems stable... Grabbing a USB HDD and backing all up before it dies again.. Wish me luck.

I ordered a new custom PC to be built for my Wife and it is due in two days and I didn't buy the offered OS, hopefully I can get the W10Pro back.

I will reply in a few days as to success, fingers crossed. Again, thanks all.

EDIT: While backing up the important stuff it froze again. Try as I may for an hour or so it never lived again :tear:
I have ripped the guts out of it now and saved anything I might use and I remembered to take out the genuine Win OS DVD from the old optical drive. I am feeling like I need to bury this old friend :tear:

EDIT: A day or two later. New PC is up and running quite fast too on start-up. I installed the W10 Pro without a problem but activation failed. Read about and tried a few fixes but eventually called MS, spoke to 'front of house' and was transferred to a technician. He activated W10 Pro remotely using the W7 Ultimate key I believe (I was called away while he remoted in so I didn't see all his doings).

Oh, and the reason he gave for me not being able to activate locally was that my W10 Pro DVD had the original software and there'd been new 'versions' since then, He left me the link for the Windows 10 October 2018 Update so I am updating now.