Radeon R9 285 - unlock to full GPU is possible

[trodas]

First let me clarify that I did not (yet) have the knowledge or even verified information, that this could be possible. But please bear with me and consider the information - maybe someone can spot the differences and help others improve the GPU performance.

 

So, in recent AMD materials for APU Carizzo was pictured a GPU Tonga, witch is present in Radeon R9 285 and feature 1792 stream processors, 32 ROP units and 256bit wide memory bus:

 

AMD GPU Tonga

 

However the catch is, that the die size of Tonga is 359 mm², witch is only slightly smaller that his predecesor, GPU Tahiti with it's 365 mm².

 

How does that matter? Well, there is very likely to be plenty of deactivated parts, giving the die size. Some people claimed, that AMD confirmed for them, that physicaly Tonga boast 2048 stream processors, not only 1792 active ones.

 

But there is something even more serious: from the picture is clear, that there is 2048 stream processors (32 CU) - and that there is, in fact, SIX 64bit memory bus controllers, witch means 6x64bit = 384bit wide memory bus is possible!

 

Now it is unclear, how many ROP units are actually on the chip: it could be 32 as in Tahiti, but it could be also 48 to simplify the memory interface - ROP units and memory controllers could be wired directly, as it is done with other chips.

 

So all in all it means, that GPU Tonga have the possibility of same power, as GPU Tahiti PLUS it have faster tesselation and delta compression. If there is 48 ROP units, then at same clocks as GPU Tahiti, this fully unlocked GPU Tonga could give about +20% of speed...!

 

If the number of ROP units remain at the Tahiti levels, it will give about 10% speed increase over Tahiti - eg. R9 290X card.

 

...

 

The fully active GPU Tonga will probably get marketed as R9 380X and the release data is unknown, but there is another thing that is possible: unlocking the chip DIY hacking.

 

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Yes, we cannot change the memory bus interface (making memory bus wider is practically equivalent to creating a own card from scratch) on current R9 285 cards, but since these stream processors are deactivated likely by bios or some switch component(s) on the GPU itself, we can - theoretically - unlock the 2048 stream processors, witch could provide still a significant boost in the performance

 

It will be different to have a 1792 or 2048 stream processors - even the number of (at least active) ROP units remain at "low" 32...

 

Inspired by: http://www.pcgameshardware.de/AMD-Radeon-R9-285-2G-Grafikkarte-259969/News/Tonga-GPU-mit-256-Bit-Interface-und-32-CUs-1160632/

Edited June 3, 2015 by trodas

[Taloken]

Interesting !

 

 

So if a R9 380X "Full Tonga" can reach a R9 290X, maybe there are same surprise in Hawaii (seems like future R9 390X) which can get 980 perf only by unlocking ?

[trodas]

Dunno. It all boil down to whatever the chip do have additional components or not. You need the hi-res image of the chip structure to determine if there are additional inactive parts or not.

 

For example GTX 980ti have inactive parts also - because activating them means that it beat Titan X without overclock, witch is what nVidia does not want for selling reasons.

 

Also matter, how these parts of the chip are deactivated. If there was, for example, laser cut... then all is hopeless. If there is not a laser cut, but a bios or resistors/capacitors driven change on the top of the chip, then unlock is possible.

 

...

 

Another good example was the double precision. For the professional AMD cards it was unlocked, for the consumers segment the real double speed precision calculations was locked down. Of course to prevent them being used as the professional cards. Also with some research it could be determined, how the precision speed is locked and unlock it

[K404]

I imagine that for the amount of money involved (the difference in the cost of parts) AMD will make pretty sure it's not within the hands of DIYers.

[trodas]

Yes, this is a possibilty. However the same possibility is, that for cost-effective approach, it is all about just some resistors on the GPU or it is even just a bios lock. That would be easiest way to do.

 

I remember, that some nVidia cards could be unlocked from consumer to pro versions by just two resistors and other bios - and that was it.

[K404]

Which ones and how long ago?

 

BIOS lock is not good enough in 2015, not for the amount of money "at risk." AMD know enough about the hardware mod community to not make that mistake I think

[TiN]

that some nVidia cards could be unlocked from consumer to pro versions by just two resistors and other bios - and that was it.

 

Yea, it was ... oh wait, 15 years ago (GeForce2).

Since GeForce3 GPU silicon is fused at manufacturing/assembly process, and no bios/resistors would help to unlock it.

 

There is some software locks based on simple VGA name detection in some CAD programms, which easy to activate just by changing name in INF, but that's rather an rare exception , than possibility.

 

So in two words , try it and tell us your success, otherwise...neeext

[rsnubje]

There was this thing not so long ago though.

http://www.eevblog.com/forum/chat/hacking-nvidia-cards-into-their-professional-counterparts/

[trodas]

Also very recent case - Radeon R9 290 can be unlocked to R9 290X:

http://www.overclock.net/t/1443242/the-r9-290-290x-unlock-thread

 

So in theory... things can work. Also - reading the changing of GTX 690 to Quadro K5000 by changing the device id of 0x1188 makes me remember, that Forceware 45.28 beta drivers did not support FX 5600XT card, so I just added the support by editing the nv4_disp.inf file by adding the FX 5600XT recognition into them

So things like that are quite well possible still up to todays. Setting device ID by resistors is interesting. Hacking the drivers install to see that device as another device is also possible. In my case the drivers see "FX 5600XT" as "FX 5600." Simple. Works. Period.

[TiN]

Having device ID from quadro does not mean that actual quadro features will work

Try it in software which uses those and see what happen. So changed name of card to Quadro/Tesla don't really unlock anything except that fuzzy warm feeling

[rsnubje]

Well, what about the HD 6950 to 6970 unlock It's still more recent than GF2. But I figure you were talking about Nvidia.