I "Unlocked" my PII 350.

[Lynxen]

I stumbled over something really cool when i was trying out my old PII300 "Klamath" (0.35micron 2.8vcore 66mhz fsb) in my MSI bx board. Quite soon i was boored i didn't get the old hag over 4.5x75mhz. So i dropped back my PII 350(Deschutes 0.25micron 2.0vcore). When i booted i saw this:
http://lynxen.mine.nu/bilder/pII/1.jpg
At first i thougt that it was just a bug in the bios, afterall it's a MSI. But when lilo (im running linux on it) hang with jibberish over the screen i got suspicous. Rebooted it, hmm still 466mhz (strange btw, 466=96x4.85... suspects it is running 433 wich is 96x4.5. Wich just happends to be the multi of the old hag PII300.... And then lilo didn't load at all. Hmm Harddrive corrupiton.... Pci must have been at 96/2! 48mhz pci is enough to kill the most of the hdd:s out there.... So i booted a gentoo rescue disc and as a final confirmation i saw this: http://lynxen.mine.nu/bilder/pII/3.jpg
I can't boot any windows to take wcpuid screenies atm will try to get a HDD that will witstand 48mhz pci to the weekend.

Standard speed: 3.5x100
http://lynxen.mine.nu/bilder/pII/2.jpg

The tools:
http://lynxen.mine.nu/bilder/pII/6.jpg
http://lynxen.mine.nu/bilder/pII/7.jpg
http://lynxen.mine.nu/bilder/pII/4.jpg
http://lynxen.mine.nu/bilder/pII/5.jpg





Ain't to shabby huh :)

Perhaps this trick will work with any high multi 66mhz cpu? Would be really cool. :) a 733celeron with 11 multi :) Combined with a overclocking friendly 100mhz celeron :) Could lead anywhere :)

[enzoR]

so how did u unlock it?

[Lynxen]

Originally posted by enzoR
so how did u unlock it?

That's the thing i just swapped the cpu! (After setting the speed to manual on the 300 in this case 4.5x66 or 4.5x75) And then i just plugged in the 350! And the 350 booted with 4.5multi!

[Teus]

I thought the multiplier was hardware locked and could only be ovverridden by altering 4 lines on the PCB during the RESET signal: A20M, IGNNE, LINT1, and LINT0

http://www.sandpile.org/impl/pics/intel/p2/p2/fake_bot.jpg

it's a bug for sure

[saaya]

it only worked on a few P2s though :(

i still think it is possible to unlock P4s, its just that nobody really tries... if you go through all the pins and check what they are doing during bootup im sure you could find a way to unlock them... its just a bunch of work...

well if you have a P4 ES its even easier, you could check whats the diference between the es and a normal P4..

i know that some people managed to change the multis of their mobile P4s, it only worked every 3rd or 4th boot though and was set back to normal after a reboot...

[Lynxen]

Maybe a bug, but it's for sure running att 96mhz fsb wich is straaange as i only can set 100-103-105-112 mhz for a 100mhz cpu and 66-68-75-83 for a 66mhz cpu.