Last month AMD amazed us by overclocking a LN2 cooled Phenom II to 6GHz at a press event, but a new report from Tom's Hardware indicates the retail parts may not be that spectacular.
The site received a Phenom II test sample and the highest they could overclock the chip with LN2 was 4957MHz:
Although AMD says nearly 6 GHz is achievable on the new Phenom II, we were not able to attain that frequency. However, with the helpof Jmax, we managed to reach 4,957 MHz. Remember however, that the 940 Phenom X4 BE II, is running at 3 GHz natively. We ran the processor on a Gigabyte motherboard based on AMD 790GX with DDR2 utilizing a cooling system with liquid nitrogen. At this point, based on what AMD tells us, the processor may have a higher potential, but it has an issue of locking at temperatures below -70 °C. To verify that the processor was stable at 4.9 GHz, we conducted some tests and it completed a SuperPi 1M run in 17,769 sec.