I used the Microsoft Media Creation Tool. I don't believe the ISO was corrupted upon download. I'm trying it again, but I don't think this will solve anything.
The October image is running flawlessly so far. No BSOD's, no freezing. I've been trying to see if I've installed anything since then that might have a deleterious effect, but haven't seen anything obvious other than the updates from Microsoft.
The 8.1 image will reinstall without issues. It is already activated, so that is not a barrier to using it. Also, I don't think the old keys get blacklisted. My copy came from a Windows 8 upgrade, (I did a clean install with it, following a few instructions on the net), and then the key changed when it was upgraded to 8.1. I can install the original Windows 8 in another machine I believe, though MS might not agree with that interpretation.
And I see Dee has answered while I was typing. I can adjust voltages easily enough but my system has been stable in the past before the updates. Stable enough to do video encodes overnight or do Prime95 overnight also. There is something with the updates that is screwing with my system.
I've tried updating drivers where it was possible, but this had no effect.
Also, freezing issues are not uncommon with Windows 10. I've been doing some searching on the subject.