About ThinkPad Z61tWhen the battery is removed, the CPU frequency will automatically drop to 997 (multiplied by 6).

Let me tell you the real reason. You think you are still using alternating current, but you just removed the battery. It's not that the frequency of the battery is reduced due to the power saving mode, so you will be surprised. First of all, I will give you some official advice on thinkpad. You don't need to remove the battery when using alternating current. First, when the voltage is unstable, the battery sometimes acts as a UPS. Because it is protected from charging below 96%, you don't have to worry about charging every time you connect AC power. Second, removing the battery will affect the weight distribution of the whole notebook, but it is not good either. If you want to maintain the battery, just charge and discharge it completely every two weeks. As for what is said on the internet, you don't have to worry about it, like what BT hurts the hard disk. It takes 12 hours to charge the mobile phone for the first three times. These are all old calendars from N years ago, and so are laptop batteries.

Now let's talk about your problem. I tested the frequency of installing and removing batteries of R400, X6 1 and X200 series when the thinkpad notebook is connected with AC power. The answer is yes, they are all down-frequency. I haven't tested the Z series, but I called Lenovo customer service to ask this question. The customer service tested their machine, and the frequency was down. The answer is the intervention of hardware. In other words, the battery is a part of the hardware and has nothing to do with adjusting the BIOS and power management. That is to say, when using alternating current, whether the battery is charged or idle, it is part of the hardware by default.

Your frequency has dropped more than mine. My X200 T6 CPU can only unload the battery at the highest frequency of 1.4G, and the result is1.73g. This should be the machine design problem of Thinkpad, but I don't know about other series.

The conclusion is that it is necessary to use batteries to reduce the frequency, and it is also necessary for these models to use AC power to remove the batteries. I … have been troubled by this problem, but your problem can be tested again and run in a high compliance state.