I didn't have any issues with F7. Or F4. F8 was horrible. Constant freezing. The F9a and F9b are great. The F9a has a new RAID BIOS (not sure why it was downgraded in the F9b). If I had to recommend one it would be the F9a. It has been the most stable and overclocks the best and the RAID BIOS boots much faster.