Clearing the CMOS resets the BIOS to the manufacturer defaults. It can be a great help if you are having problems booting the computer. Unfortunately, I doubt that it will help much with the freezing issue. But you can certainly give it a try.
Updating the motherboard drivers, updating the device drivers, and doing a fresh install of the operating system have the best chance of correcting the problem. The headache in this problem is that you can't really predict where the software incompatibility is located. It can be in the BIOS, in can be in a driver. or some corrupted file in the operating system.
Another possibility that may or may not apply is installing a new motherboard without performing a fresh install of the operating system. In essence the old version the operating system would still be using the drivers from the previous motherboard on the new one. That would cause instability problems like freezing and crashing or blue screens.