This is not DOM 2 issue. Its windows issue. Windows will default to 60 Hz for every game/program that doesn't set its own refresh rate as some sort of protection from damage in case your monitor can't support it.
There are some programs out there that help you set refresh rate for each resolution that will work in any game/program.
One tool for NVidia graphic cards is NVRefresh and you can find it at
http://www.nvrt.org/
I don't know which util is for ATI graphic cards but I’m sure there are some Users on this forum that can assist you.