MemTest86 Freeze After Test 0

Background information:  swapped out a CPU during an upgrade (old CPU DDR3-1333, new CPU DDR3-1600).
After that the system was booted using an Ubuntu Live CD without any obvious problems, but ESXi installer was crashing with Pink Screen of Death (PSOD). Next step was to test with MemTest86 (in this case V8.1 build 1000). The system would repeatedly freeze on Test 0 [Address test, walking ones, 1 CPU] with no errors reported. To fix, all that was needed was a CMOS / BIOS reset (to defaults). After that MemTest86 and ESXi installers ran through without any problems.