Latitude E4200 weired CPU clock speed.

I just checked CPU clock with CPU-Z on my Latitude E4200 with Core 2 Duo SU9400 and found something weired.

It is 1.4GHz processor and the lowest clock speed it would go down to is 1197.1 MHz and it will go up to 1596.1 MHz.

When I run this laptop with battery only or set power setting to power saver, the clock speed will stay at 1596.1 MHz and will not change. (actually over clocking it.)

Another interesting thing is Core VID goes lower when clock speed is high and go higher when clock speed is low. It will be 0.875V at 1596.1 MHz and it will be 1.050V at 1197.1 MHz.

Is this just a bug in CPU-Z or is this how it is supposed to work in new Speed Step?

 

I would say it's probably a bug in CPUZ. Try installing RMClock and see if that gives you different readings.
THe SU9400 should have 3 speedstep levels - 1.4ghz, 1.2ghz, and 0.8ghz. It definitely won't go up to 1.6ghz, and the voltage shouldn't be higher at 1.6 than it is at 1.2.
One possibility is that the processor is cutting the CLOCK in half, but the multiplier is actually increasing. Therefore, say, your CPU had a clock of 100mhz, and a multiplier of 14 (total arbitrary numbers), to get 1.4ghz. What I'm thinking is that to get to it to 1.2, it just cuts the multiplier to 12. However, maybe, to get to 800mhz, it increases the multiplier to 16 but cuts the clock in half, to 50mhz. That would explain the lower voltage.

Either way, there's a 99% chance it's a software issue.