Screen flashing when dpms tries to turn off the screen

[Richard Shaw]

Ok, Fedora 18 actually installed quite smoothly on my wife's new Acer
V3-551 w/ ATI 7640G graphics after fighting to turn off safeboot for
about 3 hours.

One major oddity though is when the system attempts to turn off the
screen for power saving, in the console it actually flashes black and
some sort of patterned grey. When in X the screen does go blank but
the back-lighting just flashes on and off.

Google failed me here but I may not have figured out the right keywords.

Anyone else seen this?

Thanks,
Richard