Nothing but problems with 5.x on my x-86 machines. I've got one that is working on 5.12 so far, but tried 5.9 and 5.11 first and it would reboot three or four times per hour. On another machine 5.12 would reboot, so I went back to 5.6. I thought that was fixed as it had been running for ten days, but tonight it locked up too. 5.x seems to be complete junk to me, but I believe I cannot run 4.x with the Intel dual-core processors in my machines.