Thanks for the advice,
The memtest ran for 15 and 1/2 hours, after 4 passes found 0 errors.
I cannot give it any more time than this right now.
Nvidia drivers got to the unloading and loading part of installation, and caused BSOD (.zip attached).
The Realtek drivers were hard to locate.
I saw another guy had similar issues - sorry for posting in his thread (there is nothing in the BSOD forum rules to say, "do not post in another person's thread") - I was hoping that he had found a download.
The drivers cannot be found using term, "RT640 NT". They are Realtek GBE PCIe drivers: here
I am installing the drivers again now.
Hopefully the graphics driver will not cause BSOD on installing again.