Works very well. I am getting over 440 Mhash/s on HD 5870 (1000/375) with -k phatk AGGRESSION=13 WORKSIZE=256 VECTORS BFI_INT and about 416 Mhash/s on poclbm. However my other HD 5870 running at 950/375 with same switches only hashes about 410 MHash/s with phatk while poclbm gives about 400MHash/s.
This worked well for me! Thanks for this tip man! +1: I have 3 5850s and these settings added like 20 Mhash/s while on my 6850 +10Mh/s! Cool!