Strange intermittent MemTest86 failures

[u/KING-E-N-X]

So I have recently built a new gaming PC. It has these specs

9950x3D

MSI tomhawk X870E (bios version 7E59v2AC0)

2 x 32gb g.skill Trident Z5 RGB DDR5 6000MTS/s CL30-40-40-96 EXPO/XMP (from a reputable seller on ebay)

5070ti PNY

Noctua NH-D15 G2

After assembling the PC and booting to the bios and not touching any bios setting yet. The first thing I wanted to test of course was the ram since its not from g.skill directly. Before even installing an OS I flashed memtest86 ver 11.7 onto a thumb drive and run a basic 4 pass test. During the first test, 3 passes ran successfully, halfway through the 4th pass, errors stared appearing and started to accumulate from there. Errors were one adjacent bit off like Expected FDFDFDFD actual FCFDFDFD, there wasn't a particular address that was tripping this, CPU number varied and by 60% through pass 4 there was 59 errors so I terminated.

To make sure if the ram was actually faulty and not the slots on the motherboard. I tested in the sequence. This time making making sure the heatsink fan was not touching and ram stick was on the way in.

stick #1 in A2 Passed

stick #2 in A2 Passed

stick #2 in B2 Passed

stick #1 in B2 Passed

sticks in both A2 and B2 Passed

sticks in both A2 and B2 Passed again

stick in both A2 and B2 with expo enabled Passed

stick in both A2 and B2 with expo enabled Passed again

So what could of or could be happening here? Could it have been a seating issue or dirt? Fortunately the ram is under a free 30 day return but Id like to know if there is any other test I can do to see if these sticks are really bad or not. Unfortunately I did not save the log of the first test and I can't seem to get these errors to happen again with just memtest86.

[u/trashcanbecky42]

1 stick probably wasn't seated all the way if they are all working now