I have a 600E which is PII 400mhz. I recently purchased a PIII 650 off ebay to make the switch. Here is what I did.
1) Swap out the processor.
2) Disabled L2 Cache
3) Installed Power Leap to enable L2 on restart.
Voila! The 600E runs the PIII 650 at 500mhz, totally stable.
I investigated the whole issue on these forums and over at wimsbios and from what I can conclude, there are no stock 600E thinkpads that are "speedstep" enabled. From the sound of it, the 600X may or may not be speedstep enabled, depending on the revision of the motherboard.
http://www.wimsbios.com/phpBB2/viewtopi ... highlight=
So being the speed freak that I am, I decided to try and modify my CPU to always run at the higher speed.
4) I performed the speedstep tweak to the CPU board.
5) Upon reboot the computer still only runs at 500 mhz stable.
I read some more on wimsbios and a user there "wmarcusm" wrote a program to force the speedstep on a 600E. I figure sure, I'll give it a try since I already modified the hardware.
6) I went to
http://home.pacbell.net/wmarcusm/deepsleep/ and installed version 1.4 of the deepsleep utility. When I run the utility it bumps my CPU from 500-->600. This was checked using CPUZ. Now I figure either I was robbed on ebay and the PIII is actually a 600, OR something else is limiting the full blown 650 from running. I am still using the onboard RAM and PC66 in the laptop, so there is a good reason to believe that the board or bios is somehow limiting the speed to maintain the stability.
It runs hotter than normal under full load, but still stable as hell on PC66 RAM. Why the long post you ask? I just wanted to point out that under the DeepSleep utility which is all software, it forces the speedstep on a 600E as long as the CPU has been modified per Katch's directions on his TP mod site. The program is just brilliant!
Here is my mod on my CPU, [censored] those are hard to solder!
http://img96.imageshack.us/img96/1607/d ... 8ao.th.jpg
I forgot to mention that the CPU mod is not for the squeamish! It was quite challenging, however even if it didn't work, the CPU still seemed to work okay at the lower speed. I was not able to "test" my mod until after running the deepsleep utility.