I know you said that you checked the health of your SSD, but did you use the manufacturer's program to do so? I find SMART tables aren't nearly as accurate for solid state drives as they are for spindle drives.
It's unlikely that it's the CPU. I recommend, if you're able, to grab a copy of Parted Magic and boot into that live environment to see if the issue persists. Any live distro will work but I highly recommend PM since it is packaged for troubleshooting.