updated 04:25 pm EDT, Thu May 26, 2011
Lenovo ThinkPad X220 has throttled CPU issue
Lenovo's recently released ThinkPad X220 notebook is suffering from a throttling down CPU, Lenovo admitted on its forums. This occurs even despite the max performance mode being enabled and the device plugged in. The CPU will go down to its lowest state, and the issue is likely to affect the T420/T520 notebooks as well.
There are ways to get around this, though they come at a cost. The more extreme method is to disable Intel's Speedstep or CPU Power Management in the BIOS. The former forces the processor to work at a high speed and voltage which leads to the battery draining very quickly. The latter method has a less significant effect on battery life, and uses between 2.5W and 3W more than when it's enabled.
A similar issue plagued older ThinkPads but the fixes developed for them in Windows do not fix the issue in the X220's case. A BIOS update may be the only true fix for the issue.
When the CPU drops to its lowest performance level, whether it's the base 2.1GHz Core i3, the range-topping 2.7GHz Core i7 or anything in between, random write speeds of the SSD and HDD are significantly reduced as well.