Most Conroe Step 4/5 (B0/B1) ES cpus can change to a lower cpu multiplier. For example:
E6600 ES can do 6x to 9x. Depending on board and bios you maybe able to do it via bios.
But here's a sure fire way of doing it in windows using Crystalcpuid and it's inbuilt MSR Editor and Intel Enhanced Speedstep Control function.
Download Crystalcpuid from http://crystalmark.info/download/index-e.html
and open Crystalcpuid's MSR Editor and enter MSR Number 00000x1a0. Click RDMSR and it should output 2 sets of values. Copy these 2 sets of values to the below empty input fields as shown.
In the below input field box, change the 2nd set of values from 0x62840489 to 0x61850089 and hit WRMSR button. If you have 'Show Confirmed Dialog' enabled it should ask you are you sure, hit OK.
Now you should be able to use Intel Enhanced Speedstep Control to adjust the cpu multiplier below the rated max.
You have to do this each reboot of windows.
FCG is working on a driver/app to do this and more, so if you feel like beta testing it go here http://www.xtremesystems.org/forums/...d.php?t=106258
This will only work with ES cpus and not retail cpus.