ntoskrnl.exe SYSTEM_SERVICE_EXCEPTION 00000000`c0000005

Solution
Several hours may not be enough - it's a long time, but I had RAM that didn't show any errors after an hour or so. I left memtest to run overnight and came up with errors. It's not usually common practice to need memtest to run that long.

Also, folks suggest it's best to run memtest on one stick of memory at a time. If you can, run memtest overnight on one stick of RAM to see what comes up from it. If no issue, repeat the process on the second stick of RAM the next night (or if you're away from the computer during the day for a long stint of time).
Several hours may not be enough - it's a long time, but I had RAM that didn't show any errors after an hour or so. I left memtest to run overnight and came up with errors. It's not usually common practice to need memtest to run that long.

Also, folks suggest it's best to run memtest on one stick of memory at a time. If you can, run memtest overnight on one stick of RAM to see what comes up from it. If no issue, repeat the process on the second stick of RAM the next night (or if you're away from the computer during the day for a long stint of time).
 
Solution