How to: Non-Reference HD6950 1GB/2GB BIOS flash shader unlock mod

Lorien

Supreme [H]ardness
Joined
Aug 19, 2004
Messages
5,197
This is a step-by-step guide by Asher2 @ bitcoin.org forums, which was based on an original idea by SlaveOnDope @ Extremeoverclocking.com.
http://forum.bitcoin.org/index.php?topic=20634.msg289672#msg289672
http://forums.extremeoverclocking.com/showpost.php?p=3901976&postcount=13

Radeon HD6950 Chewing Gum mod

What is this?

This is a hardware mod that allows you to flash your 6950 BIOS. 6950s can be thought of as coming in 3 flavours; those with a BIOS switch, those without a BIOS switch that allow flashing, and those without a BIOS switch that don’t allow flashing. This guide is for the last group. Always try just flashing first to see if it works. I STRONGLY recommend using atiflash for this, not winflash. This is because you may cause problems if you try with winflash and fail, but atiflash will generally just deny the flash and leave the card unchanged. This happened to me.

If you don’t know how to back up your BIOS and make a modified version, go find that out first!

So, whats the mod all about?

This mod is simply shorting some pins on an IC that allows you to flash your BIOS. This mod is temporary – you can remove it once you have successfully flashed your BIOS. I am going to go into detail for every step for those that are nervous about doing it. You can skip towards the end if you know what you’re doing.

What do I need?

Your 6950, a screwdriver, a small piece of wire, and some chewing gum.

Chewing Gum?

The credit for this mod goes to SlaveOnDope here. When I tried this mod, I had a lot of trouble looping the wire through the legs of the IC and stopping them touching the adjoining legs. Admittedly, it was in the wee hours of the morning and I was very tired. I came up with an easier method that gets the job done quickly and allows you to remove the mod easily even after you have replaced your cooler on your card.

Here is how it’s done...

This was done with a Sapphire series 6950. The procedure will be the same for all cards as far as I know.


dscn2656o.jpg

Here’s what the Sapphire card looks like, get a nice soft work surface to prevent damage.

dscn2657h.jpg

Unplug the fan.

dscn2658yb.jpg

Flip the card over and remove the 4 cooler screws.

dscn2659mz.jpg

Separate the cooler from the GPU and locate the IC as indicated.

dscn2661j.jpg
image2af.jpg

These are the two pins that will be bridged across.

dscn2667a.jpg

Notice two things in this image. The first is that a tiny ball of chewing gum has been put on top of the IC – this is where the name ‘chewing gum mod’ comes from. Also notice that there is a small piece of wire below the card. This is about 1cm long with the plastic removed from each end and the ends bent at right angles. This is what we are going to use to bridge the legs of the IC.

dscn2654p.jpg

Stick the wire to the gum so that the bent ends touch the legs of the IC. It may take a tiny bit of fiddling to make sure the wire is in contact on both sides. I used tweezers as I was too clumsy with my hands.

dscn2676h.jpg

Put the cooler back on and flash your BIOS! Remember to plug the fan back in! You can see here that the mod is visible when the cooler is on. When you are done, just pull the mod off with tweezers or whatever without needing to remove the cooler again.

Good luck, have fun!
P.S: The only real variable in this whole operation is if the actual Cayman GPU will succesfully unlock the extra shaders. That is simply a matter of luck.
 
Last edited:

-Sn1PeR-

2[H]4U
Joined
Dec 26, 2002
Messages
2,950
That's pretty badass. Is there any reason not to just solder that wire in as a permanent installation?
 

Lorien

Supreme [H]ardness
Joined
Aug 19, 2004
Messages
5,197
You don't need it after you've flashed the BIOS and the unlock is successful. But yeah, If you want to keep it to be able to experiment with different BIOS you can make it permanent. It'd be like a ghetto dual BIOS switch.
 

XacTactX

Supreme [H]ardness
Joined
Dec 13, 2010
Messages
4,133
Nice guide, "+ rep".

You can also use a silver circuit trace pen and connect the pins by making a path on top of the IC.

I've done this on an XFX 6950 1GB rev. A3 and can confirm that the mod itself works exactly as described, though unlocking will depend on the core like Lorien said. I purchased mine from TD in mid-June and it was laser cut, for anyone who might be wondering.

That's pretty badass. Is there any reason not to just solder that wire in as a permanent installation?

Warranty and resale purposes.

You don't need it after you've flashed the BIOS and the unlock is successful. But yeah, If you want to keep it to be able to experiment with different BIOS you can make it permanent. It'd be like a ghetto dual BIOS switch.

I think it just turns off hardware write protect which normally prohibits you from flashing a BIOS. It doesn't allow you to switch in between different ROMs.
 
Joined
Dec 4, 2005
Messages
664
Hmm i was about to buy a 2GB reference, wonder if I would be better off ordering a non reference and doing this mod. Guess we dont have much success rates. Also does this require full flash, and will it cause issues like some reference cards had with memory timings?
 

Furyan

n00b
Joined
Jul 12, 2011
Messages
10
P.S: The only real variable in this whole operation is if the actual Cayman GPU will succesfully unlock the extra shaders. That is simply a matter of luck.

Any way to improve those odds, eg. which cards have Cayman's that are known to unlock (or known to stay locked)?
 

Lorien

Supreme [H]ardness
Joined
Aug 19, 2004
Messages
5,197
Hmm i was about to buy a 2GB reference, wonder if I would be better off ordering a non reference and doing this mod. Guess we dont have much success rates. Also does this require full flash, and will it cause issues like some reference cards had with memory timings?

Why would you flash it with a 6970 BIOS? that's simply retarded. All you need to do is apply a BIOS which unlocks the shaders or edit your own, RBE can do either quite easily.

Kind of a big risk for 1-3 fps gain.
People are not doing this only to play silly video games. Bitcoin mining has caused a huge demand of AMD video cards and the 6950 is one of the best for it specially since they can be unlocked.

Any way to improve those odds, eg. which cards have Cayman's that are known to unlock (or known to stay locked)?
Not really, unless you know a tester at TSMC or the AIB assembly line that can tell you which batch of chips are good. I doubt they would be willing to share that information to the public. Besides you lose nothing by trying this method since the card will not be bricked, the BIOS flash will simple error out as described in the guide.
 

Furyan

n00b
Joined
Jul 12, 2011
Messages
10
Not really, unless you know a tester at TSMC or the AIB assembly line that can tell you which batch of chips are good. I doubt they would be willing to share that information to the public. Besides you lose nothing by trying this method since the card will not be bricked, the BIOS flash will simple error out as described in the guide.

Ah ha! I didn't realize it was a luck-of-the-die thing. Thought it had to do with specific models of chip. How interesting.. thanks :)
 

Dulak

Limp Gawd
Joined
Oct 12, 2005
Messages
316
Just ordered a sapphire 2 gig dirt 3 version ... may give this a go once it comes.

couple questions ...
- when removing the hs/fan; is it easy to reattach this? any problems ...
- any idea which bios works the best - like to use one that just unlocks shaders not oc at all.
 

Spare-Flair

Supreme [H]ardness
Joined
Apr 4, 2003
Messages
7,471
Nice job! I saw that version locally for $250 CAD before they ran out of stock. I should have picked it up!
 

Lorien

Supreme [H]ardness
Joined
Aug 19, 2004
Messages
5,197
I sold a couple of brand new 6950s 1GB for $210 shipped a couple of weeks ago and someone else was selling a pair of used ones for $180, you just didn't look hard enough.
 

Spare-Flair

Supreme [H]ardness
Joined
Apr 4, 2003
Messages
7,471
I just did this mod on the exact same card and it allowed me to flash the BIOS but I had no luck unlocking the extra shaders.
 
Joined
May 18, 2009
Messages
934
I know this is an old thread but I just did this on a XFX HD-695X-ZNFC that had the bios locked and it unlocked the shaders and tested good!! +rep for the OP
 

repilce

n00b
Joined
Oct 28, 2012
Messages
1
I have this exact card I just got, upon making shorting the correct pins (my dot on the bois chip is in the same location) The card will not boot, start the system up and it just sit's there with fan at 100%

I have tried twice, I used solder with a wire, both times same result, but upon removal the card works fine.. ? anyone out here ran into this?
 

jahara

n00b
Joined
Dec 3, 2008
Messages
54
I tried this on a Sapphire nonreference 2GB and I'm able to flash now-- beforehand it would never flash. However, even upon flashing I am stuck at 1408 shaders. Reading the BIOS off the card shows that the 6970 shader hack is present so I'm guessing my card is hardware locked :(
 
Top