T-Rex Nvidia LHR Booster

Since the release of version 0.22.1 on 20th of September, T-Rex now includes a mode that tries to partially lift the limitations of mining using Ethash and Etchash algorithm on Low Hash Rate (LHR) GPUs. 

Since the release of version 0.24.0 on 7th of October, and 0.24.1 on 10th of October, the miner now also includes a dual-mining mode, a low-power mode for LHR unlocks, has changed the tuning parameter, although previous ones are still converted to the new percentage-based value, automatically detects and tries to unlock LHR-affected GPUs even with no lhr-tune value set, and will attempt to increase the performance if not triggering lock for a prolonged period of time.

Dual Mining explained

Since the cards are LHR series, the hashrate is limited in some of the algorithms. The locked cards are in some cases able to achieve higher performance when mining two separate coins instead of the same locked one. This is done by having separate algorithms, separate pools and separate wallet addresses (in most cases), and the performance can be higher than during mining only with one of the locked algorithms, like Ethash or Autolykos2.
The implementation available in T-Rex in particular allows users to mine ETH at 30% the theoretical non-locked hashrate and 70% of the non-locked hashrate of another coin, like RVN with KAWPOW algorithm, CFX with Octopus or ERGO with Autolykos2. Please note that hashrate might be limited during ERGO mining too, so it might be worth trying to experiment with another algorithm if ETH+ERGO dual-mining slows down too.
Here are the config examples and how-to-setup for these dual-mining modes:

Booster explained

Since the cards are LHR series, the hashrate is limited in some of the algorithms. The booster, also called an "unlock" of peformance is attempting to run the cards at hashrates higher than the lock allows, but below the speed at which the locking mechanism will "notice" the "violation" and attempt to lock the performance.
Think of it as a gray zone between the target allowed by the drivers and the point where sensitivy starts, zone in which you're still not limited, but if you go a bit higher than that — you'll be forced down by a lot.

The booster also has a mechanism to counterplay the locking: if the miner detects hashrate going down significantly, it will pause mining on the GPU to "reset" it and attempt to run at a bit lower tune in order to not trigger the locking mechanism again. 
During this process the reported hashrate will fluctuate and mostly stay on the lower side because every LHR lock will cause the miner to pause for 20 seconds to unlock the GPU, so you may need to wait till it finds stable settings.

Miner configuration

For ETC mining the Simple config can be used and miner will auto-detect and adjust the unlock values used.
For ERGO mining, the miner does not automatically detect the locked cards so you need to configure the miner separately, as discussed below.
  1. Open the Worker's config by going to the workers list and clicking the wrench icon next to the worker you want to configure.
  2. Scroll down to the "Default miner" entry and select T-Rex.
  3. In Simple configuration mode, choose the coin, pool and wallet that you want to use.
  4. Press the pencil icon to edit the generated configuration in advanced mode.
  5. For ETC mining:
    At the end of the configuration, change the } to , "lhr-tune": "4" }
    Difference between older values used, which are now automatically converted to the new values below:
    0 - disabled (use for non-LHR cards)
    1 - lowest hashrate, low chance of LHR lock
    4 - recommended starting value for most LHR cards
    8 - highest hashrate, high chance of LHR lock
    New values:  Range between -1 for automatic behavior and 0 to disable LHR detection for the card to 100 for the max hashrate possible. The starting value recommended for regular mode is "lhr-tune": "71"
    For the low-power mode replace } at the end of the config with , "lhr-low-power": true, "lhr-tune": "-1"} 
    To disable auto-tune entirely, also replace the last } with , "lhr-autotune-mode": "off" }
    To adjust the time interval for each auto-tune change, replace } with , "lhr-autotune-interval": "X" } where X is the window in minutes, i.e. 5
  6. For ERGO mining:
    At the end of the configuration, change the } to , "lhr-tune": "80" }
    Difference between values used:
    0 - disabled (use for non-LHR cards, or the ones that aren't affected by LHR under the overclock you use)
    99 - For cards with GDDR6X memory (3070Ti, 3080, 3080Ti)

    For cards with GDDR6 memory (3060, 3060Ti, 3070), the manufacturer of the memory chips matters. However, it is only being reported on windows at the moment, since Nvidia currently doesn't provide a public access point in the Linux drivers with that information, so you would need to judge by results or try to find out based on serial/part number of the cards, or,  by disassembly of the cards to see the brand logo on the memory chips themselves, which is the most reliable but most time consuming method.
    91 - good starting point for GPUs with GDDR6 non-Hynix memory
    80 - GPUs with GDDR6 Hynix memory, these aren't working well with the unlocker, so you may need to try even lower setting

Instead of value 4 in the given example, you can set different value for each of the GPUs. For example, "lhr-tune": "0,0,4,0" will not enable the booster for cards 0, 1 and 3, but will enable for the card #2 at the starting value.

Here's a full example config with the tune configured: 

{ "pools": [ { "user": "(WALLET:ETC)⁣", "worker": "(WORKER)⁣", "url": "(POOL:ETC)⁣", "pass": "x" } ], "no-nvml": false, "api-bind-http": "", "json-response": true, "pci-indexing":true, "retries": 3, "retry-pause": 5, "timeout": 500, "no-watchdog":true, "algo": "etchash", "exit-on-cuda-error": true, "exit-on-connection-lost": false, "lhr-tune": "4,3,0,7,2" }

Operating system configuration for the Booster


On windows-based systems, you manually need to install drivers for cards. The cards have been tested to work with driver version 471.68 and you can find other versions on Nvidia's official driver search.

msOS settings for LHR series

You can use the new versions of msOS to use the LHR series cards with new driver version included, available on msOS Version Archive. For most motherboards msOS version 1.4.10+ should work, but if your system requires newer kernel (mostly for newer motherboards, like H510 Pro BTC+), you can use msOS version 1.7.5+.

If you are already using an older version and would prefer to not reinstall OS completely, while adding LHR Nvidia GPUs to your system, and they turn out to be not detected on msOS, update drivers with nvidia-update command: nvidia-update --install 470.63.01 
Driver updating details are also available here.

If after driver update and reboot, your GPUs are still not detected, then re-check BIOS settings:

  • UEFI
  • PCIe GEN2
  • Above 4G Decoding

On msOS side, you can try this command: pci-realloc

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