Unlocking a week 39 or later AMD CPU (Update)
Eversor 6 May 2004

As you should be aware AMD started locking all of it´s cpu´s, except Athlon 64 FX. That means our happy socket A days are a bit doomed, or were, the solution to this problem isn´t as easy as it should be, but at least now it´s possible to change mults in locked cpu´s.

This guide apply´s to all socket A cpu´s that have L3 multiplier locked, wich include Applebreds, Thortons, Bartons and Toroughbreds.

The problem posed to us overclockers is that our dear 2500+ bartons were the first to become multi locked from factory. Tough they can, and still are, overclocked to 3200+ simply by changin FSB from 333 to 400, some bartons tend to be excelent overclockers and 2.4GHz+ are possible with these cpu´s, and not all of us have ram and boards that handle +200MHz.

Since they became come out locked, many started to look for a solution to re-enable L3 bridges, but no pin as been discovered as re-enabling this, maybe L3´s simply aren´t connected the way they were before, wich left us with no solution.

But AMD forgot (thankfully) to lock also the L5 bridges wich lets us change our cpu to a mobile XP or a Athlon with MP support.

Luckilly one of OCW members, Petr, has made a software that allows chipsets that support mobile AMDs to change multplier in windows...

This will work for all cpu´s, tough this guide is only intended to allow muli change in locked cpu´s.

The first step is to pick the cpu and look for L5 bridges, once found the 3^rd L5 bridge from the letf is the one to paint. That will make your XP a Mobile XP.

The unlocking process is easier than i originally tought. You don´t have to be carefull in filling the pit, or unhiding the bridges. Simply take a pencil, and scratch each bridge, i have attained more success by filliing also the pit with the same pencil, since it seems to be making better contact.

Tried it with at least two cpu´s and had zero problems.

This will enable your cpu to use PowerNow! Multipliers, and change them on the fly using CPU MSR. You may get it at: http://www.cpuheat.wz.cz/html/Tweaks.htm , also there´s a essencial article that explains how to use CPU MSR and changing all cpu´s to mobiles or Mps.

The PowerNow! Support will depend if your board supports or not FID_Command changing, if it doesn´t, most nForce 2 don´t seem to work, you shall need to edit registers with WPCREDIT.

If your mod with nForce2 is sucesseful please mail me at eversor@iol.pt to send me a pic of your nForce2 PCR configuration, so a solution can be found for all nForces 2.

SiS and VIA chipsets are supporting this without any problems, especially SiS´s ones, VIA´s may require register editing wich is described by Petr in his CPU MSR page. The first mod I´ve done was in a K7S8X-E+.

One problem arises now, all desktop cpu´s have a default L6 maximum PowerNow! Multiplier of 11x, to change this L6 bridge cutting is required, as they are allways all uncut.

UPDATE: Painting the 2^nd L5 bridge(the one left to the mobile bridge) opens all mobile multipliers from 3x to 24x. Carefull, if your board boots at maximum mobile multiplier, like SiS ASRocks, your cpu will try to boot at 24x.

Having the cpu oriented so that L6 is to your right the bridge config for multiplier is described here: http://fab51.fc2web.com/pc/barton/athlon-e23.html#L6.

So if you would want to open till 12x multiplier you see in table CCC:C, wich mean, looking at your cpu this way you should cut the forth bridge from left.

If you want access to 6-24x, simply cut all bridges, carefull, with a bad cpu in K7S8X-E+ this would be very bad has with 100MHz bus the cpu would boot at already 2400MHz!!!

UPDATE: The new K7S8X-E+ Mobile Multi BIOS always boots at 3x, the lower multiplier available. Select at least 5x in BIOS, at 200MHz 3x and 4x don´t work.

Careful, as setting a different maximum multiplier may boot your cpu at it´s maximum, so you should set your FSB a bit lower to test first. Some boards should boot at maximum, other boot at lowest, and some at default, 11x in 2500s, and the right multiplier has then to be set in windows.

Testing in K7S8X-E+ made the cpu to boot at it´s maximum multiplier, wich I set at 12x.

Aopen AK79D-400 left it at 11x, tough it detected the maximum PowerNow multiplier to be 12x, could set it tough, motherboard isn´t supporting P-state changing.

I hope this could be implemented by bios, as I think if manufacturers like abit become aware of this, they may use this to trick the board to use all cpu´s as mobile in order to use PowerNow! Multipliers.

I'm testing a way to change mult´s so they can be set for, hopefully in all boards, to boot at selected multiplier.

More news here as they come...

Related Articles :

• Enabling up to 24x in multiplier for modded AthlonXP
   
• Unlocking Barton Week 39

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