I run 2 6990s and 1 hour ago i was getting about .5 hw errors per second and full speed on the newest version.

Then there was a power brownout and all my equipment froze and restarted. When I restarted, the newest version gave me 75-85% of speed under the same settings and 1000 hw errors per second. However on the old version which I switched back to now, I get 100% speed still.  I had this problem before, and what might have fixed it is reseating the cards. But if thats the problem why does the old version work fine?