Test 2 causes reboot, all other test run and pass

[LinearMap]

I'm having an issue with my system. Sometimes underload it just reboots, spontaneously with no warning. I'm using memtest86 to help diagnose the problem. All of the the (non experimental) test run and pass except test 2. Test 2 reliably causes a system reboot as it starts the memory range test. I've included a snip from the log file memtest generates:

2023-01-11 19:43:21 - Running test Forum (Test 2 [Address test, own address])
2023-01-11 19:43:21 - MtSupportRunAllTests - Setting random seed to 0x50415353
2023-01-11 19:43:21 - MtSupportRunAllTests - Start time: 7180 ms
2023-01-11 19:43:21 - MtSupportRunAllTests - Enabling memory cache for test
2023-01-11 19:43:21 - MtSupportRunAllTests - Enabling memory cache complete
2023-01-11 19:43:21 - Start memory range test (0x0 - 0x86E000000)


At that point the system crashes so the log ends. Does anyone have thoughts on what that might mean?

The motherboard is an MSI Pro Z390-A.

Thanks

[David (PassMark)]

We aren't aware of any issue in the software.
Test 2 hasn't changed in a long while.

So might be BIOS bug (bad memory map) or an actual hardware failure.

Initially treat is like a memory error.