I tried setting up a new system today with a 5850. I used the 2.1 guide for a 64bit system but my CPU went up to 100%. I've read a bit about there being a bug, but it doesnt seem to be affecting everyone. Just because of this, the 2.4 guide is far better. But I have also seen how some have gotten really good results from the 2.1 setup. Does anyone have any suggestions? I have used to search button already and it didn't seem to turn anything up except to upgrade from 2.1 to something else.
I think the CPU bug is in the driver not the SDK and you can use 11.6 but not 11.7 or later. This is what I found for myself using Ubuntu (2.4 and 11.6, high cpu usage bug went away).
Also be sure to use the newer Phoenix 1.6.2 instead of 1.48. When I finally got around to updating I immediately got a 10 MH/s gain on each card.