Well, this seems to be too late to reply, but I totally agree with ibm and amn's opinions.
I happened to check my cpu with Intel processor identification utility and found that my CPU runs at 1.19 GHz.
Well, I first thought that I may need to change my power options, but nothing changed.
Then, I tried the utility on my desktop and it showed the desktop cpu was running at its full speed.
So, I was googling if there is any other case like I found.
Here it is~!
ibm clearly mentioned the exactly same problem. Well, some may say why these guys don’t use battery but use 65W adapter only?
But it is my preference. Like some others, I would like to preserve my battery. As I have used several different laptops, based on my experiences, I think using battery in the laptop all the time does shorten the battery life.
Anyway, my point is that Lenovo should have mentioned about this issue in the manual, specification, or flyer.
Some may like to use the laptop longer, some may want to use it with full speed, and the other may want lighter battery or adapter. I believe that depends on who is using it. However, as there are specifications for parts such as adapters, cpus, rams, network cards, etc., when I purchased a laptop, I had an expectation that my laptop would run at xx speed, and my battery would last for xx hours, and my laptop takes xx hours to charge. We got the information from the specifications, flyers, and manuals. If anything is different from the advertisement, it also should be noted.
If I knew it about the cpu speed issues with power sources, I must have had 90W adapter too.
It's like advertising that a SUV car runs 35 mpg without saying when it is on highway. But they do say it even if it is very small and on the corner of a flyer.
So, at least from now on, Lenovo should put that info something like “CPU runs 74% with 65W adapter, 100% with 90W adapter, and 100% with battery”