Hard Undervolting Mobile Pentium 4 Lower than 1.2v

[podrik0]

Please help am reviving the talks from the following thread:

http://forums.anandtech.com/messageview.aspx?catid=28&threadid=1527123

The experts on their I hope you still about!!!

I have the Mobile data sheet

http://img14.echo.cx/img14/8989/untitled5dh.gif

However I don't understand which ones I want to bend or connect or isolate etc

I am current running 1.2v after I broke the VID4 pin.

I am currently running 1.2Ghz @ 100FSB

BIOS is very limited so am having to do it this way

I know this processor will still run 1.2GHz @ 0.9v or 1.0v but prefer 0.9v

So can some help me out finding how to get my processor being fed 0.9 or 1.0 instead of 1.2???

I am running passive and the temps are 65C so need this desperetly!

Any info need I'm happy to give

Thanks!

 

[stevty2889]

Can you find the data sheet for a normal desktop CPU. I am assuming you are running this chip in a desktop board. The desktop boards and mobile boards have differant VID's, so you need to find the data sheet for the desktop VID's. I am not 100% sure on this of course, but according to the mobile data sheet, VID4 is already disconeted for 1.2v on a mobile, so I'm assuming it's differant for a desktop board.

 

[stevty2889]

It would appear that for a desktop board, the VID's are differant, and the lowest is 1.1v. Since you needed to break VID4 to get 1.2v, it would appear that a 1 is an isolated pin, and a 0 is a connected pin. I found the data sheet for P4 VID's here. Since the only thing differant between the 1.6v default, and the 1.2v is chagning the VID4 from a 0 to a 1, it would appear I am guessing correctly. You should be able to get down to 1.1v by isolating VID3, VID2, and VID1. I wouldn't recomend breaking them off, if you can find a way to isolate them, as I said I am not 100% sure, but I am pretty sure.

 

[podrik0]

Thanks will give it a go now

 

[stevty2889]

Let me know how it goes..

 

[podrik0]

Yup worked THANK YOU!

Issues though on the way I broke off:

VID4 VID3 VID2 VID1

Then Windows XP would freeze some random point of setup similar with other boot programs.

So I placed coil wires from the VID 2 and VID 1 to make slight contact?

Then it worked

And the voltage is 100% still at 1.1 - 1.13v in ASUS Probe + BIOS

Idle temps are now 42C passive!

So many thanks for your experise knowledge!!!!

I have no way of explaining the setup problems though!

 

[stevty2889]

Cool, glad it worked. I may try something similar with mine, lol but my hands shake so I don't know if I could work with those tiny pins.

 

[aidanjm]

Originally posted by: stevty2889
Cool, glad it worked. I may try something similar with mine, lol but my hands shake so I don't know if I could work with those tiny pins.

you can use the hollow tip of a technical pencil (where the lead comes out, when you click on the end of the pen) to enclose a pin and then bend it from side to side

 

[TStep]

Just got done hacking another mobile Celery in this manner To the OP, the conductive paint in window defogger kits can also be use to connect the points as well. I've used the stuff from Autozone.