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Disabled AMD Radeon GPU compute units may be software unlockable

By Scorpus ยท 8 replies
Aug 6, 2015
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  1. Thanks to the expertise of a bunch of modders over on the Overclock.net forums, it may be possible to unlock previously-disabled compute units in some GCN-based AMD Radeon graphics cards.

    The unlocking process works with some 'Pro' SKU graphics cards utilizing either AMD's Fiji, Hawaii or Tonga GPUs, such as the Radeon R9 Fury, R9 390/290, and R9 380/285. In these cards, AMD used a cut-down version of a GPU with some compute units (CUs) disabled either through firmware modifications or permanent laser-cutting.

    A tool from Overclock.net member tx12 called CUINFO allows you to determine exactly which CUs have been disabled in your GPU. Using this information, you can flash a new BIOS to your graphics card that attempts to fully or partially unlock disabled CUs. If, for example, you could unlock all of the disabled CUs in an R9 Fury, you would essentially end up with an R9 Fury X.

    Naturally there is limited success with unlocking CUs, as some have been disabled because they were damaged during the manufacturing process, maximizing total yield. Unfortunately there is no way to tell if a CU has been disabled for this reason, or simply whether a CU has been disabled to create a lower-end SKU.

    Re-enabling CUs does lead to increased performance in cards where this is possible, although the unlocking process almost certainly voids all sorts of warranties. While it can be an interesting experiment for an enthusiast wanting to get the most out of their GPU, unlocking CUs definitely isn't recommended for everyday users.

    Permalink to story.

  2. VitalyT

    VitalyT Russ-Puss Posts: 3,456   +1,735

    This is a stupid idea.

    As a far as I know, each CU in the GPU is tested right on the assembly line. Each CU that failed the test is disabled. When the minimum number of operational CU-s is reached, the chip is discarded. All the chips that pass the test are sorted according to their success rate and marked for the corresponding product line.

    You are talking about unlocking CU-s that very likely have failed their test due to production flaws. The latter in today's GPU manufacturing can easily reach 20%, hence the natural selection process.

    Even If you end up with a single malfunctioning CU enabled, I may have to throw your graphics card into the garbage. Like I said, that's a stupid idea.
    Last edited: Aug 6, 2015
    Evernessince and Adhmuz like this.
  3. timtiminhouston

    timtiminhouston TS Rookie

    Not true! If you flash it and get errors you flash it again using trial and error until you see which compute units are good. A lot of down binning occurs to meet sales expectations, so a lot of GPUs that could have been Fury X's will become Fury's. It just gives me another reason to consider upgrading cause I love flash-able parts. In fact, this may be the single reason I get a Fury. I still might wait for the Fury Nano and just get a better after market cooler and OC though.

    I promise you that this unlock will lead to increased sales; I have bought several past cards for exactly the same reason (but it is hit or miss). I love a challenge, and I love modifying stock firmware. To hell with a warranty, I quite smoling so I could afford this hobby so I win even if the card dies.

  4. VitalyT

    VitalyT Russ-Puss Posts: 3,456   +1,735

    Provided that you have the original BIOS, which may be difficult, if not impossible.
    I rest my case.
    Evernessince likes this.
  5. timtiminhouston

    timtiminhouston TS Rookie

    I meant to say I quit smoking to keep this hobby, and yes I have destroyed several cards, but not like this. I tried soldering on new VRMs and have never gotten it to work. Only on older cards do I break out the solder iron.
  6. Evernessince

    Evernessince TS Evangelist Posts: 1,786   +1,007

    I'm going to have to agree with VitalyT, chance are the CUs are disabled for a reason. I think it could be interesting if it was proven wrong though. If enthusiasts could prove a decent success rate. The Fury would be the best small configuration card by far.
  7. timtiminhouston

    timtiminhouston TS Rookie

    Well, in case anyone hasn't noticed, AMD is in a bad way as of late. There may have been a small cost involved in laser cutting to disable dies. Furthermore, they are built on an extremely mature 28 nm node process (28 nm has made it through three generations now) so I suspect they are getting near perfect yields. They just can't sell but so many high end cards. I hope they are going back to software disabling cores cause it seems pretty shitty to me to spend extra energy to completely disable what is most likely good cores at lower speeds.

    I could be wrong and this could be a marketing rumor, I am wrong at least 49.999 percent of the time according to my wife, and she does a good job of proving it. But I have never flashed a card I couldn't reflash; backing up the current rom is the first step in every guide I have seen. But again, it is only for people like me that just want to open things up and see what is inside. I wont buy a product I can't tweak. Everything I buy I modify.

    Oh, and I spend in excess of 2k a year on gaming related goodies-my wife has every receipt I might add. I am a good customer and if this is true I will be tempted to get a Fury. If not I will wait for the Fury Nano which will have all CUs but at lower clocks. I lean towards it being true because it just makes sense that if the Fury x and Fury Nano are full uncut parts, why cut the one sitting between the them?

    But then again, I am a glass half full type of person. It is tempting...you really can't lose being stuck with a regular Fury.
  8. Squid Surprise

    Squid Surprise TS Evangelist Posts: 1,315   +537

    No, it's NOT stupid... let's say the tier 1 card is supposed to have 64 CUs, and the tier 2 card has 48.... now let's say a card comes off the assembly line with 4 CUs "broken".... It has 60 working fine though.... can't sell it as a tier 1... so you disable the other 12 and sell it as a tier 2... it's easy cause you simply tell the tier 2 BIOS to automatically disable every CU over 48 - so you don't need to manually do this for every tier 2 card (some will have 49CUs, some 50, etc.... all the way to 63 operational CUs)

    Now, we buy this Tier 2 card at a far cheaper price - flash a new BIOS (custom made by the dudes at overclock) which gets rid of the "disable all CUs past 48", and get ourselves FREE PERFORMANCE - in this case 25% more (12 CUs being 25% of 48 for those of us less mathematically inclined).

    Yes, it will be a bit of work and risk - anyone flashing a custom BIOS on a Video Card should already know this, however!

    It's kind of like overclocking back in the days of the 486.... wasn't always pretty, but you could get lots of free performance... if you knew what you were doing!
    Uvindu and timtiminhouston like this.
  9. Mike Gray

    Mike Gray TS Member

    Bios flashing AMD cards from second to first tier models is a fine, old tradition, and once the bleeding edge modders have sorted out the necessary software, it's usually quire safe. If your card is flashable, the software will say so; if it isn't you just leave it be. Out of 3 second-tier AMD cards I've owned over that last years, I've been able to flash two of them - the other wasn't, so I just used it the way it was.

    Typically, certain models (almost always: REFERENCE models) and certain vendors vendors (this changes from card to card - check the appropriate threads on overclock.net!) offer better chances that others. I'm currently working from a Bios-flashed reference 290 from XFX that's been running as a 290x for a couple years now. Add in custom water cooling with an OC @ 1225, and I'm very satisfied with the purchase. Back in the day, I bought the XFX model specifically because that company's cards were known for successful flashes.
    timtiminhouston likes this.

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