Description of problem:
Installed fresh Fedora 20, then updated (kernel 3.11.10-301.fc20 -> 3.16.3-200.fc20, among many other things) and restarted.  The X server won't start with the 3.16.x kernel; it gets as far as the Fedora logo, then the screen goes blank.  If I press Escape to see the bootup progress, it hangs immediately (i.e., before the Fedora logo would have gone away).  No login screen appears, and no text-only TTYs are available either (e.g., CTRL-ALT-F2 does nothing).  After a hard reset, I can reboot using the 3.11.x kernel, but never the 3.16.x kernel.

Version-Release number of selected component (if applicable):
kernel-3.16.3-200.fc20.x86_64
xorg-x11-xinit-1.3.4-1.fc20.x86_64
xorg-x11-xauth-1.0.9-1.fc20.x86_64
xorg-x11-server-common-1.14.4-11.x86_64
xorg-x11-server-Xorg-1.14.4-11.x86_64
gdm-3.10.0.1-1.fc20.x86_64

How reproducible:
Unknown

Steps to Reproduce:
I don't know how reproducible this is, or even what information to post; I will do my best to follow up if necessary with such information as may be required.

Actual results:
System crash with no keyboard recognition or interaction of any kind.

Expected results:
Normal startup of X11 server and GDM.

Additional info:
This bug is similar to Bug #1147543, but the symptoms are different (i.e., complete lack of output vs. limited text-only output).