I am having this weird issue. I used to be running a dual gtx 460 setup on this machine and rarely had problems with this (except nvidia oops and other random shit breaking on rare occations when switching X-windows sessions once a month or so).
Anyway I have since tried both a gtx 650 ti and a gtx 670 in the machine and I am having issues.
Basically once I start X it stays running without any problems but as soon as I try to stop X (either control-alt back space, or kill the process) starting a second X session (which used to work) or switching to the console (control + alt + f1) X will start using 100% cpu usage on the machine and it can’t be killed (even with signal 6 or 9).
When its in this state my PC starts beeping (with its PC speaker) about every 30 seconds. After 3-4 times it does 3 beeps in a row. Its really weird because I ran a gtx 670 on my home machine that used to be the identical motherboard and almost identical OS install and I never had these issues.
Any idea what could cause this? Again it works fine when its got a gtx 460 in it.
There is nothing being printed in the Xorg.log and nothing being listed in dmesg… just some PC speaker beeps and X using 100% cpu.
Here is the Xorg.log from when I started up a single monitor X session and tried switching to the console and got the beeping (nothing of importance showing up here):
And the bugreport log that was ran where nothing has happened on this boot:
One difference I can think of is with the gtx 400 series I was running a significantly older driver (270 series).