For Socket 478 only
Northwood Mobile Pentium 4(-M) CPUs - No MSRs involved, uses pin GHI# to switch multipliers
Prescott Mobile Pentium 4 CPUs - MSRs are involved, doesn't seem to use pins to switch multipliers (most likely to work)

This is a guide for enabling SpeedStep on motherboards that don't support it, which may or may not work as SpeedStep requires BIOS support, chipset support, and CPU support. Try it at your own risk, I have gotten BSoDs before.

Steps
1) Download Read & Write Everything v1.7 from this link: http://rweverything.com/downloads/RwPortableV1.7.zip (requires XP SP3 x86 or 2000 SP4 with blackwingcat's extended kernel)

2) Extract it out from the zip, and place it anywhere that you prefer.

3) Run Rw.exe, and then click on the icon that looks like a flipped PGA478 CPU. It has a text labeled as 'MSR' on it.

4) A window with the name of 'CPU MSR Registers' should pop-up, once that loads, click on the 'User' tab.

5) Click on the 'User' icon/button, and then copy the text below to its text box (not the text box found on the left side of the 'Add' button). Click on the 'Done' button once you have entered them in.
IA32_PERF_CTL=0x199
IA32_MISC_ENABLE=0x1A0

6) Double-click on the newly created register called 'IA32_MISC_ENABLE', now you should be able to see 64 bits shown in a small pop-up window. Do not click on any of the registers yet.

7) Double-click on the number below register 16, it should be then flipped to '1'. This forces SpeedStep to be enabled, but be aware that this may cause a BSoD. Make sure that you have nothing important running at this moment. Once you have done that, click on 'Done'.

8) If it doesn't trigger a BSoD, congratulations. You have just enabled SpeedStep, assuming register 16 didn't reset itself back to '0'.

My last request if you have made it this far: did you notice anything in the IA32_PERF_CTL register? Are there any numbers in it? If there are any, what are they?

SpeedStep/Turbo Boost drivers
Turbo Boost Technology Driver v1.2.0.1002 - Vista/7
https://dl.dell.com/chipset/R275031.exe

Turbo Boost Technology Driver v1.0.1.1002 - XP/Vista/7
https://download.lenovo.com/ibmdl/pub/pc/pccb … es/6ips01ww.exe

SpeedStep Applet v3.4 - 2K
https://dl.dell.com/utility/INTEL_SPEEDSTEP_A17_R190149.exe

SpeedStep Applet v3.3 - 2K
https://dl.dell.com/utility/R150537.exe

SpeedStep Applet v3.2 - 2K
http://download.lenovo.com/ibmdl/pub/pc/pccbb … es/79sue3us.exe

SpeedStep Applet v3.10 - 98/NT4/2000
http://download.lenovo.com/ibmdl/pub/pc/pccbb … es/1ysue1us.exe

SpeedStep Applet v2.30 - 98/Me/NT4/2K
http://download.lenovo.com/ibmdl/pub/pc/pccbb … es/spdstp1g.exe

SpeedStep Applet v2.10 - 98/Me/2K
http://download.lenovo.com/ibmdl/pub/pc/pccbb … es/spstep2k.exe

SpeedStep Applet v1.30a - 95/NT4
http://download.lenovo.com/ibmdl/pub/pc/pccbb … es/spstepnt.exe

SpeedStep Applet v1.10 - 95/98/Me/NT4/2K
http://download.lenovo.com/ibmdl/pub/pc/pccbb … es/utspstep.exe