Pentium M overclocking

pinmod

Laptops based on the Intel 915 chipset have a 533MHz front side bus and ship with a matching Sonoma processor. Dothan laptops only have a 400MHz FSB. If you pull the BSEL[0] pin on a 400MHz FSB Dothan CPU to low you can trick the 915 into thinking it has a 533MHz FSB CPU. This will gain you 33% more processor speed. Almost every other pin on the CPU is a ground so you just insert a U-shaped piece of wire into the processor socket to connect the two pins. If the system becomes unstable you may have to bump up the processor voltage (which involves another piece of wire). In the article, Dan Zhang is able to take a 1.8GHz Pentium M to 2.4GHz. It’s a pretty simple mod, but you have to go out of your way to do it since Sonoma laptops never shipped with a 400MHz FSB CPU.

[thanks jodathmorr]

24 thoughts on “Pentium M overclocking

  1. To someone with one of these machines and a need for just a little more go power this is an incredible break!

    Nice work!

  2. “Should Prime95 display a failure message in less than 30 minutes or so, you will need to increase voltage by taking your laptop apart again and connecting a higher VID[x] pin to VSS.”

    On the instalation page at the bottom there is this wording. I am worried (maybe i didn’t read the before section right) that increacing is the wrong way to go. Would it not make more sense to go _down_ (decrease) the voltage by removing you r pin mods or moving to another position.

    As i have a mac i dont think i will do this any time soon but good hack none the less.

  3. I actualy having a mProssesor problem.
    My prossesor is 1.2ghz but it only runs at ~800ghz, even pluged in. I went into the bios and it only fix it slightly. Any idea?

    It’s a compaq Evo N410c with XP pro and I installed from a standered XP disk, not the one it came with (I got it second hand wthout the disk)

  4. #2:
    Increasing the voltage is what’s needed because at the higher speed it will require more power for stability. Decreasing would make it even more unstable if it’s crashing under prime95.

  5. #7 goto compaq’s site and search for the speed-step fix (I believe the problem is that if you hit 100%cpu it will lock the speed-step at the lower speed), alternatively update windows. It is a known XP bug and has been patched.

  6. @#6, your cpu speed on a laptop with a pentium m is actively throttled to save battery and reduce heat. Even plugged in, it may not go all the way up, because it is not being used. Check your cpu speed with CPU-Z, then run prime95 or superpi to see if it changes under load. It may be that you just haven’t caught it under load with the multiplier up. Unless it’s being used, it will not scale up, even plugged in.

    If you continue to have problems, consider downloading notebook hardware control from this website. You can use it to adjust the cpu speed etc.

    http://www.pbus-167.com/chc.htm

  7. Pretty cool, but I’d be more interested in a way to underclock my Sempron, damned thing gets hot and the fan is kind of loud when I’m in class. No options in the BIOS.

  8. my dell 700m has an intel pentium m 725 1.6GHz Dothan 400MHz bus speed. The chipset is an i825. Could I do this mod?

  9. Just in case anyone is interested, the ASUS Z71 series of barebone laptops actually have a dip switch to do this for you. I tried it and it works great.

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