Hi guys,
Having a weird issue that I've been trying to resolve for a while now.

My system (is supposed to) run 4 x 8GB RAM. When booted in this config, the system runs as expected for what can be weeks. File shares, dockers, VM's all working correctly. I've found that when running a parity check with 32GB RAM, the server will stop working but the GUI works correctly - I can switch between Dashboard/Main/Shares etc - but in the background nothing is working. I'm unable to access the shares or use media players etc. I'm also unable to reboot or shutdown once it's failed this way.

RAM speeds are set to 1866MHz as per recommend settings at https://forums.unraid.net/topic/46802-faq-for-unraid-v6/page/2/#findComment-819173

I've tested all the RAM - initially a 24 hour memtest with 32GB didn't flag any errors. I've since run each matched pair of RAM modules in both slots 2+4 and 1+3 (4 tests total), running a parity check each time as well as leaving the system running for a few days afterwards. The parity check completes correctly and the server carries on running without issue.

When the system freezes, even though I can navigate to the diagnostics page, I'm unable to download anything. I set up a localsyslog in hopes it might capture something, and have attached it. The most recent failure was found in the morning of October 4th.
I've also attached diagnostics from the recently rebooted 32GB system. No parity checks scheduled for another few months so I'm hoping it stays up until I can figure out a solution.

Thanks in advance!

syslog-192.168.1.201.log tower-diagnostics-20251005-1440.zip

That suggests the board is having stability issues with all backs populated; look for a BIOS update or lower the RAM speed.

I was running the most recent BIOS when I set up the server a few months ago, but has been a new one since. Updated that and then set RAM to a lowly 1600 MHz. First parity check with 32GB completed as normal.
Thanks again @JorgeB