PickleRickSanchez

Also a possibility, but typically (though, not always) a failing power supply won't result in a freeze.
Sadly, the only real way to test that is slap a new power supply in and see what happens. Great if you have a spare laying about, not so much if you don't.

or RAM.
 
Run MemTest86+ for several complete passes to rule out bad RAM
https://www.memtest.org/
 
After that, if the RAM checks out, then it's probably a flaky mobo

The only thing that changed is the chipset ... and you already have the amd chipset drivers installed, so windows simply detected a different chipset, searched for drivers, found the ones installed already are compatible and reused them.
Probably have same onboard audio chip, same network card, same everything.
 
It should work fine, but if you get random crashes or reboots, maybe consider reinstalling the operating system.
 
Had you move from AMD to Intel motherboard, with different chipsets, and lots of other things, that could ne a "shock" to the system and cause problems, making some people recommend a reinstall.

I mean changing a motherboard doesn't have result in a reset. 
If any problems start to occur then sure. If it's fine leave it. 

More or less. The GPU and display is the centerpoint. The 2600 is still a really good PSU