I have recently bought a new machine with an AMD Threadripper 2990wx CPU (not overclocked), 4*16GB RAM, Gigabyte X399 Designare EX motherboard, an NVIDIA RTX 2080 GPU and a 1200 Watt PSU. I have Ubuntu 18.04.1 installed on it.

I noticed that when I put very high load on it, the machine will freeze up within a few seconds to the point that it responds to nothing except for the magic SysRq codes which I use to reboot it. Even switching Num Lock doesn't work!

I've been reading a lot about various Ryzen bugs and have tried the following to resolve the issues with no success:

add "idle=nomwait" to the kernel command line (although this is supposed to fix a freezing issue at idle)
add "rcu_nocbs=0-63" to the kernel command line
upgrading to kernel from 4.15.0-45-generic to 4.18.0-15-generic
installing the "amd64-microcode" package
use the "ZenStates" utility to disable the C6 core state
go into the BIOS settings and disable the C6 states from there
go into the BIOS settings and disable "CPU Performance Boost"
adding "processor.max_cstate=1" to the kernel command line
I can't find anything else to try anywhere, and it seems that no one has come across the same issue. I've seen the Ryzen segfault bug and the idle freeze issue but not a high-load freeze issue.

I encountered this when I tried to compile my own kernel. When I run make -j modules, the compilation starts and I see all cores jumping to 100% load, and after 4-5 seconds the machine freezes. If I use make -j 64, I still see all cores on 100% but the build completes with no issues.

I went over /var/log/syslog, /var/log/dmesg, /var/log/kern.log and any other log file I could find there but couldn't find anything that has anything to do with this. It just looks like everything is ok and then there's a pause of a minute and a new kernel boot output starts, no error message, no warning, no oops/panic messages, no soft lock messages.

Any ideas on what this could be and what I should try next?

Thanks!

memtest

+1 on memtest.

From bitter hardware experience, next try slowing things down - cpu and bus speeds. Then repeat memtest, if that failed first time. There's also a PSU 'power good' line and that will spring a reboot pronto. You're trying, I gather, to isolate & return a faulty part. Substitute what you can, check contacts, & conductivity (Electrical and thermal). Good hunting.

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