ATI released a driver hotfix for the Radeon HD 4850 and 4870. "This Hotfix improves overall performance and stability. The Hotfix includes the Display Driver and Catalyst Control Center." http://support.ati.com/ics/support/default.asp?deptID=894&task=knowledge&questionID=35298 I didn't test this exessively, but it resolved a lot of micro stuttering for me. Not the heat issue though.