This time, during reboot, the power supply started flickering on and off
Do you mean the power led on the case.
There was no indication of a power problem, in speedfan as the voltages appeared correct, although it MUST BE STRESSED that it is only a very rough guide.
It is really very difficult to advise you NOW of course.
With the graphics running and the system stable, after uninstalling the driver and the NView it was my intention to attempt to carry ouit some more checks.
IT could be the power supply, it could be the motherboard itself.
With hindsight and of course it is a wonderful thing, it may have been best to leave it running and see where we could go from there
Referring tio your post 19 - it was running OK and then 20 I installed the driver - and it crashed and then 21 - updates - IN BETWEEN the crash and installing updates - had you again uninstalled the driver.?
My best advice is - DO NOT SPEND too much. If you can borrow, beg or whatever a power supply , try it with another PSU.
The old idea of testing a PSU with a multimeter is a non starter, firstly they must have a connection made between two wires of the main connector, in order even for them to send power, that is effectively what happens when you press the ON power button on the computer.
If you connect the wrong two - it is good only as a paperwight.
Alternatively if you have access to such take the PSU out and take it to somewhere that will test it. I do not know how you are placed there but here a small local computer repair business offers such a service.
OR you can purchase a basic PSU tester for a relatively small cost.
In summary, it is difficult, to make reasonable progress ON the forum now it will not boot.
YOU MAY consider, removing the graphics card and seeing if the PSU will remain ON, with the fans running.
If replacing the graphics card results in this situation changing - then although it is NOT a positive and conclusive result, as the extra power demand may still indicate the PSU, then one MAY reconsider the grpahics.
I regret that I cannot offer more definite advice.