If you need to run a D14 cooler for a 12400f, something is SERIOUSLY wrong.
What are your FULL hardware specs including motherboard, exact memory kit model, model and age of attached storage devices.
Did you "upgrade" your old Windows 10 installation or did you do a CLEAN install where you delete ALL of the existing partitions on the OS drive (Including the hidden partitions) and then install to the unpartitioned, unformatted space?
Also, a 3-5 year old CXm power supply with an RTX 3070 is not a very good pairing. If that CXm is between 3 and 5 years old and has been run hard fairly regularly or for frequent extended gaming sessions, it might be a really good idea to start by replacing it with something substantially better. The CXm units, especially the older ones, were basically the bare minimum we'd recommend in terms of quality for anybody running a discreet gaming card of any moderately capable flavor.
HOW MANY passes of Memtest86 passed without any error? Did you run it for FOUR FULL PASSES of all 11 tests, or just one pass?