NBMiner's Nvidia LHR Booster

Since the release of version 39.0 on 15th of August, NBMiner now includes an automatically-applied mode that tries to partially lift the limitations of mining using Ethash and Etchash algorithm on Low Hash Rate (LHR) GPUs.

Version 39.3, released on 18th of September added a second mode for semi-unlocked, boosted Ethash mining known as low-power mode. This mode is also set as default.

Version 39.5, released on 24th of September added a booster for Autolykos2 algorithm, which is used to mine ERGO. This requires manual enabling.

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 unlock percentage value in order to not trigger the locking mechanism again.

Ethash

For mining with Ethash/Etchash algorithms, used for ETH, ETC, ZIL and other coins, NBMiner has 2 built-in modes, which operate a bit different and are optimal for different cards. The default unlock percentage is 69, meaning the miner will attempt to run at 69% of the non-lhr hashrate  The automatic adjustments are made in steps of 0.1 at a time, up to 10 timies, so the maximum difference is 1% of non-lhr hashrate.

Mode 1, configureable in the advanced options for the miner via adding -lhr-mode 1 is more suitable for 3060, 3060Ti, 3070 cards. It is targetting the highest possible hashrate.

Mode 2, configureable in the advanced options for the miner via adding -lhr-mode 2 and enabled by default is more suitable for 3070Ti, 3080, 3080Ti cards and is able to achieve lower power consumption and temperatures. It's especially highly recommended to use Locked Core Clock setting in ClockTune with it.

Autolykos2

With the Autolykos2 mining, the memory type and manufacturer of the memory chips matters. The mode needs to be explicitly enabled by using -lhr X parameter in the advanced config, where X is the % of maximum potential hashrate to be unlocked. I.e. -lhr 85 will attempt to run the miner at 85% of the maximum speed the cards would be able to provide, had there been no lock. The automatic adjustments are made in steps of 0.5 at a time, up to 10 times, so the maximum difference is 5% of non-lhr hashrate.

  • For cards with GDDR6X memory (3070Ti, 3080, 3080Ti), the suggested starting value is -lhr 100
  • 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.
  • SK Hynix-made GDDR6 chips don't behave well with the unlock, and the performance is poor, so it's not recommended to use the unlock on them. To disable the booster, set -lhr -1
  • With GDDR6 memory chips from other vendors (Micron, Samsung), the suggested starting value is -lhr 85

Miner configuration

In the below example we'll be setting up booster for ETH mining with default options, you can change the advanced config further with the values mentioned above, how to change them is explained below, at the end of this section.
  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 NBMiner.
  3. In Simple configuration mode, choose the coin, pool and wallet that you want to use.

minerstat - NBMiner

By default, the miner automatically applies the parameter -lhr 69 for Ethash-based mining and mode 2 set, in which power fluctuates.

The measured results with options -lhr-mode 1 -lhr 69 set are about as following, when including manual overclocking:

  • 3060 (including v2) ~27MH/s
  • 3060Ti LHR ~40MH/s
  • 3070 LHR ~42MH/s
  • 3070Ti ~54MH/s
  • 3080LHR ~65MH/s
  • 3080Ti ~80MH/s

You can press the pencil icon next to the launch options listed under coin, pool and wallet selection menus and then manually add -lhr X, where X is a number between 0 and 100 to adjust the value, including on per-card basis, separating the values via comma: -lhr 70.1,0,68.5,-1. The value -1 disables the booster for the specific card (or whole system if only one value is passed). The value 0 applies default setting, currently same as -lhr 69

Operating system configuration for the Booster

Windows

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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