Any idea why memory clock on RX570 vary a lot on Cryptonight-heavy?

[Dzeronimo]

I need your help to solve a problem with Cryptonight-heavy algo.
My RX570 4 GB works OK if I mine Ethereum (28.2 MH/s) or Monero (920 H/s). I'm using 18.3.4 drivers in Compute mode and BIOS is modded. Core/Mem clocks are 1150/1970 MHz.
The problem is that I get only around 450-500 H/s in Cryptonight-heavy algo. I'm using SRBminer (tried two different versions) for CN and CN-heavy algos. I noticed a strange thing. When I mine with other algos memory clock is stable at 1970 MHz, but with CN-heavy memory clock vary A LOT in three steps: 300 MHz - 1000 MHz - 1970 MHz. Clock changes almost every second and that's why I'm getting lower hash rate. The situation is the same if I decrease memory clock (I tried even 1850 MHz) or increase voltage, but... If I increase memory clock to 1980 MHz, clock become stable, but I'm getting memory errors and cannot mine anymore. Weird.
Any idea why is this happening?

[SpceGhst]

I believe if your memory clock or core clock isn’t holding to the speed it’s set to, it’s a power issue.  Try setting the voltage to “auto” and see if it holds the clock settings then.

[SpceGhst]

FWIW, I have a 570/4gb, Samsung memory, no bios mod (stock), set at 1205 core (default) and 1950 memory (1650 default) with auto voltage settings, and it’s getting 600 HS/s on CN Heavy...

[Dzeronimo]

I believe if your memory clock or core clock isn’t holding to the speed it’s set to, it’s a power issue.  Try setting the voltage to “auto” and see if it holds the clock settings then.

Thanks for the advice, but that didn't solve my problem. I don't think that CN-heavy is more demanding than Ethash and I can mine ETH without problem.

[Dzeronimo]

Is it possible that I'm the only one with this issue? I've tried many different things, but without success. Any new idea?

[Suslived]

Is it possible that I'm the only one with this issue? I've tried many different things, but without success. Any new idea?

It's a known issue with Cryptonight-heavy. Your hashrate will really be lower because of something about thread usage. I really don't know the technicalities behind it but just search google with keywords like "rx 570 cryptonight-heavy hashrate" then just check if your hashrate is comparable to others. As long as you are making a profit then why not eh?

[texasman86]

you should be seeing about 700 with your 4gb card... i have 8 4gb cards from a variety of manufacturers and am seeing that for all... I really think your solution is to increase the power given to your card in afterburner.

[xlm19877]

i try mining Cryptonight-heavy on all my rigs

all time i have problem like restart or freeze

this alog maybe need alot off memory

so it will run stable on 8gb gpus

[Dzeronimo]

you should be seeing about 700 with your 4gb card... i have 8 4gb cards from a variety of manufacturers and am seeing that for all... I really think your solution is to increase the power given to your card in afterburner.

I increased voltage from 0.9 do 1.1 but that didn't solve the problem. I just noticed that I have a problem only with SRBMiner and will ask in SRBMiner thread for help.