Ubuntu 14.10 freezes, what's the problem?

Question

ubuntu

Hello!
There is the following problem. There are four servers with the same configuration (on board ubuntu 14.10) and the same settings, all work well except one. This server freezes 2-3 times a day, is not available via ssh, does not respond.
It is not possible to find the problem on your own, because. my knowledge of ubuntu ends with installing nginx. I would be very grateful for your help in solving the problem.
Logs:
dmesg
syslog
there were logs... now they are gone

Answer 1

Check your memory.
If the RAM fails in the logs, you will not see anything. The system hangs before it spits in the log

Answer 2

I would try turning off iommu if it's not needed there. And so, in general, I join Sergey - the memory would be worth banishing with memtest.