Hallo my friend, i have the G1 Sniper 3 motherboard with 16gb Dominator GT, GTX680 Lightning, i7 3770K, bios f8m and the last week i have the same problem, i have the board over 6 months but i have used it less than 3 and the problem started few days ago, as you said when i restart it goes away , if i put it to sleep it doesn't cause it to happen again but its something that happens 2-3 times in 2 days. As i didn't have that problem at the start, i hope to be just the drivers (also if it was the motherboard , i think it would be more permanent and wouldn't go by restarting the pc).
I use Windows 7 ultimate x64 , i will try to make a fresh install and let you know if it will fix the problem.
I also wanted to add that when in bios on the memory selectable table choose QUICK it doesn't let me change anything on the timings on the second channel,all the settings are grey. I contact Gigabyte and they said it should let me change the top 3 or 4 top settings (which are the standard) on both channels A\B, something that isn't the case. I don't have blue screens or instabillity, i tried 4 different bios version and both bios chips i also tried other mamory. When i set it to expert it let me change everything as it should, Go figure right?