I think I had a similar problem, using the EDID option thing fixed it though. The 8-series linux drivers default to reading the EDID info from the monitor, whereas the previous versions didn't & instead went by the 'HorizSync' & 'VertRefresh' in the xorg.conf file. Although your problem occurs for both 7 & 8 series drivers. Maybe some monitors have dodgey EDIDs or old ones are meant to be probed slightly different.
Here's a link to the thread where I found this out:
I dont think 60Hz is exactly optimal by any means, at least not for me, I'd get a headache at that resolution. I think it's just a typical refrash rate that manufacturers give their monitor specs at. Oops, I just noticed its a LCD screen. I'll go and stand in the corner with my pointy 'D' hat...