Just installed 13.04 on new G780, left UEFI enabled, but wiped Windows 8 off the disk.
Whenever I boot up 13.04, the screen shows purple for a few seconds, and then just the back light shows for a few more seconds, and then the screen goes black with no back light.
While it is booting, I have to press the Function key and hold it while I press the up arrow key, which increases the back light enough so I can see the Ubuntu splash screen.
When it is done booting I can increase the back light fully with the scale showing in the upper right corner.
Not a big problem, but just kind of annoying.
PS booting Ubuntu 12.10 worked great, but no wired internet. Booting 12.04 worked the same as 13.04 with a black screen.
Formatted the 1TB disk with 5 partitions, 1=UEFI, 2=root, 3=var, 4=home, 5=swap