memtest86 Errors in some slots but not others - random bluescreens

[jajones82]

I am receiving random blue screens while using my computer...Gaming, copying files, browsing, whatever...I ran memtest86 and here are my specs/steps/results
my new build - all brand new parts

Motherboard Model Name – AsRock B450M
CPU/Processor – Ryzen 5 2600
Memory – g. Skill f4-2400c16d-16gfxr (2x8GB)
Video Card – Asus ROG RX 570 4GB
Operating System – Windows 10 Home from Microsoft website
Hard Drive – Crucial P1 CT500P1SSD8

• Reinstalling Windows multiple times, using different USB sticks
  • Blue screens persist
• I tested both sticks of RAM individually one at a time in each individual MOBO ram slots with Memtest86
  • Slot a1 and b1 both posted so many errors the test crashed each time
  • Slot a2 and b2 tested successfully each test (4 passes) no errors

Does the fact that the errors occur only in those slots mean the motherboad slots are bad?? Is that a reasonable conclusion?

[David (PassMark)]

Yes, it would seem that something is wrong with the slots (assuming nothing else changed. For example the BIOS configured the same timings and voltage each time). With a small change it is the memory controller in the CPU. And a possibility that the RAM sticks are marginal. We've been seeing a lot of GSkill marginal RAM recently that works at some speeds and voltages, but not others.

Real test is to replace the motherboard and see if the problem goes away.