using the same flags?
I keep my flags blank (use no flags) for both of the versions, so i guess that counts as a yes...
Try using:
-v -w256
I've got a couple 6850's and that's what I use. It might get you back up to 180. Almost all my cards are 6000 series, and I always use -v, and always -w with either 128 or 256, you can tweak that number to find which one works best (64, 128, 256, etc). And you can also try adding -f1, I use it on about half my cards, sometimes it makes a difference, sometimes it doesn't...