Dual mining

GPU miners can benefit from the fact that some algorithms are memory-heavy (like ethash) and others are core-heavy (like blake3) making it possible to combine them and mine the secondary algorithm at very little impact to the primary algorithm hashrate.

Dual mining can be enabled with --dual-algo parameter which should be preferred over the deprecated --lhr-algo.

ETHW+ALPH, ETC+ALPH

Quick start: see "ETHW+ALPH" *.bat/*.sh file in the miner archive on how to run it. If you are using HiveOS or any other mining OS that launches T-Rex with a config file rather than command line arguments, you need to specify your parameters in JSON, for example:

"dual-algo": "blake3"
"url2": "stratum+tcp://pool.woolypooly.com:3106"
"user2": "1qUuxVuXN2Pk4nnYTbL4qihjLWyRkVMQVYQDAajCcuPq"
"pass2": "x"

The above will set blake3 as the second algo in dual mining mode.

Behaviour and tuning

There are a few options to control the behaviour and fine-tune the performance of the GPUs in respect to how they dual mine. See the options below:

--dual-algo-mode <algo>:<tuning coefficient>

<algo> can be one of the following:

• a1 - the GPU will be mining just the primary algorithm (ethash)
• a2 - the GPU will be mining just the secondary algorithm (the one you set in --dual-algo)
• a12 - the GPU will be mining both algorithms at the same time (dual mining)

<tuning coefficient> is optional, and can be one of the following:

Tuning coefficient	GPU type	Description	Formula
rXX	non-LHR	"dual ratio" XX	H2 = H1 * <dual ratio>
hXX	non-LHR	primary algo hashrate percentage XX%	H1 = H1_max * <hashrate percentage> / 100.0
rXX:lrYY	LHR	"dual ratio" XX "LHR dual ratio" YY	H2 = H1 * <dual ratio> + (H1_max - H1) * <LHR dual ratio>

where
H1 - primary algorithm hashrate
H2 - secondary algorithm hashrate
H1_max - maximum theoretical primary algorithm hashrate

Default value for --dual-algo-mode is a12, meaning all GPUs will be mining in dual mode with default settings - non-LHR will try to maintain 98% of the primary algorithm maximum hashrate, and LHR ones will be dual mining at LHR 74 unless LHR tune values are explicitly set to a different value.

--profit-per-mh <profit_algo1>:<profit_algo2>

<profit_algo1> is the amount of dollars (or any other currency) that you expect to earn by mining the primary algorithm at a speed of 1MH/s - you can get this info from an online mining calculator, <profit_algo2> - same for the secondary algorithm.
Assuming you haven't set the dual ratio explicitly, this parameter will cause the miner to benchmark various "dual ratios" upon start up and choose the one that produces the highest earnings. This feature is only applicable to non-LHR cards. Your LHR cards will be dual mining according to the specified LHR tune values.

Example

Consider the following set of parameters, assuming they are part of a ETHW+ALPH config:

--dual-algo-mode a2,a1,a12,a12:r15:lr19,a12:r15,a1,a12:h95,a12
--lhr-tune 0,74,73,72,0,0,0,0
--profit-per-mh 0.0516:0.0012

This config translates into the following:

GPU#0: non-LHR, mines ALPH
GPU#1: LHR, mines ETHW with LHR 74
GPU#2: LHR, mines ETHW+ALPH with LHR 73
GPU#3: LHR, mines ETHW+ALPH with LHR 72, dual ratio 15, LHR dual ratio 19
GPU#4: non-LHR, mines ETHW+ALPH with dual ratio 15
GPU#5: non-LHR, mines ETHW
GPU#6: non-LHR, mines ETHW+ALPH with ETHW hashrate being approximately 95% of its max value in single mode
GPU#7: non-LHR, mines ETHW+ALPH with dual ratio that maximises profitability based on the data set in --profit-per-mh (ETHW expected profit is $0.0516/MH, ALPH - $0.0012/MH)

Tips

• Due to its nature dual mining is very power hungry, so if you want to maximise your secondary algo hashrate try raising the power limit. An even better way would be to leave the power limit at max and lock the core clock instead, for the GPUs that support it.
• Do not forget to restart the miner after changing overclock settings.