How much RAM do you have? Click Cotrol-Alt-Delete ONCE Click on the Performance Tab and check your CPU Usage. When the Motherboard fried it may have fried a RAM chip as well that they didn’t catch. Sometimes with low RAM they’ll chug along slow or sometimes a bad RAM chip will give a BSOD.
RAM size could definitely be an issue. We sent one machine in for repair and it was magically missing a chip; i.e., half its memory, once it returned.
Right click on “My Computer” to select the “Properties”. Verify that the amount of installed memory is correct.