Random freeze and reboot

Hi , hope someone can help.

Had a PC for a while, upgraded parts as and when necessary. Recently replaced my hard drives with an ssd and hard drive.

Now when I install windows 10 it installs fine onto the ssd. Then I installed the gfx card drivers (nvidia 355). Seemed OK. Then PC started to become unresponsive then the screen went black, monitor flickered between analog and digital searching. Had to hard reset.

Then the PC just won't boot back into windows, locks up or resets itself after bios screen logo and windows logo. Sometimes doesn't even get as far as the windows logo.

Temps are stable, voltages are within limits. Psu and gfx card are recent, rest was working ok with gfx card.

Wondering whether to boot in safe mode and uninstall the gfx drivers. Then download the latest from nvidia.

It's an old Intel core I7-930, Asus X58 sabertooth, 8gb ram, gforce 950 card. 500gb hard drive, 120gb SanDisk SSD.

Any help would be greatly appreciated.

UPDATE: Someone at MS via their help desk said my Win10 build was out of date, so gave me a link for a new copy.
Downloaded that then started the reinstall.

All good.

Until windows installed the latest graphics driver for my 950. Then after restarting it hung again and can't boot back into windows.

Now attempting to install Win7, to see if the problem persists. Then I know it's either hardware or software.

Install graphics drivers in Win7, same thing. Screen blank.

Card only 6 month old. Try resetting?