I'm running Ubuntu 14.04 on a DELL R320. I have no 3rd party drivers enabled. Machine boots normally, but when the login screen loads, it flashes momentarily and disappears and the monitor says "Input not supported". When I was building the machine, I've set the desktop at 1024x768 which is definitely supported by the monitor I'm using.
I've tried modifying /etc/default/grub to set GRUB_GFXMODE=1024x768 (and running update-grub after), with no change.
Firstly, is there some log files I can check to try to figure out what's going wrong?
This is new territory for me, and I've read a bit about X.org... should I be changing anything there?