Back to Archives

1.0        Introduction

This discussion concerns modifying the AMD Athlon Thunderbird and Duron processors by manipulation of the L1, L3, L4, L6, and L7 bridge contacts on the top of the processor.

 

 

 

 

 

2.0 Unlocking a Locked Processor

Early model Durons and Thunderbirds came with the processor "locked", which meant that even if your motherboard supported adjustable multiplier and Vcore settings in BIOS, your changes would not have any effect. The L1 bridges control the lockout.

 

This is an easy modification. All 4 of the L1 bridges should be closed (connected) to unlock the processor to enable selection within BIOS. Proceed to "Reconnecting the Bridge Contacts" (section 3.2.2).

 

 

3.0 Reassigning Processor Multiplier and Vcore

With todays motherboards, support from the manufacturer for some level of overclocking features is fairly common, but not a certainty. So, what are the alternatives if your board doesn't support overclocking features? Two choices are software manipulation of the clock generator and hardware modification of the board or even the processor itself.

 

To this end, the multiplier on Durons and Thunderbirds can be changed by modifying the L3, L4, and L6 bridges, and if necessary the Vcore can also be changed by modifying the L7 bridges.

 

 

3.1 The Theory

Here are several excellent articles, which explain the theory behind these modifications.

 

Tom's Hardware broke the news that the "new" Athlons could be overclocked similar to the slot Athlons (June 23, 2000).

http://www6.tomshardware.com/cpu/00q2/000623/

 

Tom's follow-up article with the details of the bridge mods (July 11, 2000).

http://www4.tomshardware.com/cpu/00q3/000711/index.html

 

Anand's article includes the discovery of all of the actual CPU pinouts (July 19, 2000).

http://www.anandtech.com/printarticle.html?i=1282

 

 

3.2 The Practice

Ok, lets dig in… literally!

 

This bridge calculator at ocinside may be helpful…

(  http://www.ocinside.de/index_e.html?/html/workshop/socketa/socketa_resistors.html ).

 

3.2.1 Cutting the Bridge Contacts

Hard modification of the Thunderbird’s bridges will require some special tools. First, you will need optical magnification, magnifying galsses or jewler's loupe (5x) should do it.

 

Next, chose your cutting device. I have already tried the bridge mod with an X-acto knife, but these proved to be unable to cut through the ceramic enough to successfully cut the bridges. You will need something with either a carbide steel or diamond tip. I chose a Dremel Tungsten Carbide Cutter (PN 9909). It has a sufficiently fine point to allow for good control (I mean, have you seen those damn bridges!).

 

Others have reported using a diamond coated micro bur. An entire set is available from Micro Mark (Part# 80919)    

( http://www.dxmarket.com/micromark/products/80919.html )

 

3.2.2 Reconnecting the Bridge Contacts

After cutting, reconnect the bridges for the chosen multiplier and Vcore. For this purpose I use automotive rear window defogger Quick Grid Repair Resin from Loctite Corp.

 

Others have reported using Circuit Works conductive ink (Part# CW2200MTP)

( http://www.chemtronics.com/catalog/catalog.cgi?action=list_products&category=7 ).

 

A toothpick shaved to a fine point is just right for applying the resin. I also found a dental pick useful for cleaning up any excess (after it dries), so you don't cross connect the bridges. Major mistakes are no problem, as the resin can be easily removed with fingernail polish remover and a Q-tip. Allow the resin to dry for about 15 minutes to insure good contact with the bridges.

 

That’s it! Reinstall the processor and see what you've got.

 

Back to Archives