mac pro
what are the key strokes at start up to get into the diagnostics. one where you hold down keys until you hear the chime?
Click on this link, Use Apple Diagnostics to test your Mac – Apple Support
If you have a Mac Pro read the Intel section.
If you have a newer MacBook Pro with a silicon chip read the Silicon section.
Olde Mac Pros would have come with two grey install disks one of which would
have included the Apple Diagnostics.