I was actually hoping for this answer, so thanks :).
1700MHz shouldn't be a real issue on the GD70, but may be on other boards. I tested the DFI DK and I couldn't even get the board to work at 1700 1M stable, whereas the GD70 allowed me to do even higher (for reference:
http://www.madshrimps.be/?action=get...61&articID=926, sorry for url, but hotlinking pictures doesn't work).
During the tests, I noted down that this issue may have been related to the overclocking itself, so increase of HTT. Could someone test for me if the memory goes equally high using the 1:4 and 1:3.33/1:2.66 divider? I would do the tests myself, but haven't got an AM3 setup put together at the moment.