Teamviewer is bad to tweak with settings.
I have a Gigabyte 990FXA-UD3 Rev.4.0 with Sempron 145 and Gigabyte r9 280x (Rev2.0) too. I managed to get 730kh/s. Unfortunately, I've no Rev1.0 to do the comparison.
Is that with 6 cards?
I've been trying BAMT out, unfortunately all my rigs took a performance hit using it regardless of board revision, so i'm back on Windows 7.