P4 = locked, so why jumper setting?

Hello all,

As far as I know, P4 CPU’s have always been locked to a certain multiplier. Overclocking is limited to FSB overclock.
But I just found a manual for one of my old RD-RAM motherboards and it has a Switch to select a multiplier for both 400 and 533Mhz busses. It goes from 16x to 24x (400Mhz FSB) and 16x - 23x (533Mhz FSB) :confused:

Are there unlocked P4 CPU’s? Or is it a useless feature? Of course it’s not a big deal to test it, but I just wanna hear some opinions first :slight_smile:

Yes there are a couple unlocked Intel CPUs floating around, but you won’t find it at any retail shop.

The jumper you’re talking about involves switching cpu bus speed and has nothing to w/ unlocking multiplier. Switching from 400FSB to 533FSB to 800FSB doesn’t change the fact that an Intel CPU’s multiplier will always be constant relative to the CPU model.


Northwood A = 400Mhz FSB

Northwood B = 533Mhz FSB

Northwood C & Presscotts = 800Mhz FSB

It also has to do with what kind of ratio that you want to OC your FSB.

I’m sorry I wasn’t clear enough, because it’s not a jumper to change the FSB. Here’s a picture of the jumpersettings in the manual. picture
As you can see, it goes from 16x to 24x. So in theory, it would be possible to use a 2,4Ghz (18 x 133), choose an FSB of 133 (another jumper) and select a 24x multi, which would run the CPU at 3,2Ghz on a 133Mhz bus. Somehow I doubt this is possible :slight_smile:
But this brings me back to my initial question; why that jumper?

To get us/you excited I suppose. There was a time when this was needed. But because the CPU’s are locked this feature is useless.

As Stoner said, there are indeed CPU’s without mp lock available. Most of them are made for testing purposes (so called engineering samples) and handed over to hardware manufacturers…