If I read the stats right on that motherboard over at NewEgg.com it supports 1066 RAM speeds natively, and anything above that is supported through overclocking.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
I don't see that model listed on Asus' Products page any longer either. Which is probably why NewEgg.com has the $10 rebate on it. Not to say there's anything wrong with the board, but it's obviously being phased out for newer models.
Point being, it shows support for DDR3 1600 by OC. So it might take some tweaking to make it work completely stable.
Tried to search for the M4A77TD under Asus tech support site. Although they had the model number listed, they had absolutely nothing listed for it (No Bios, Manuals, Tech Sheets, etc). Was going to see what they officially said about RAM speed capabilities for you. But I'm not finding anything on their site.