How to overclock GPU for Ethereum mining
Ethereum is mined using DaggerHashimoto (Ethash) algorithm. It uses a massive DAG-file loaded directly to a GPU's VRAM. This file contains all the data required to calculate the hash for the jobs given by the pool. Any card having less memory on-board than it is needed to fit the DAG file becomes unable to mine Ethereum. Its size will reach 3GB in early March 2019. All GPUs having less than 3GB will become unable to mine Ethereum at the same time. For example, GTX 1050 2GB lost this ability on June 22, 2017.
DaggerHashimoto algorithm is entirely about VRAM. All the mining stuff is both stored and done in there. In general, the higher the memory speed, the higher the hashrate, and the profit. Whereas, core clock changes are mostly meaningless in terms of profitability. It is even recommended to downclock core to lower power consumption. So, the overall tip: boost your VRAM, not the core.
DaggerHashimoto's video memory appetite makes the algorithm available almost exclusively to PC users, as it is hard to design an ASICs with fast enough RAM. Moreover, Proof of Work ASIC-resistant updates of the network keeps the GPU's role prevalent in the mining network.
How to clock it right?
Boosting a video card should be a slow and steady process involving careful monitoring, testing, and taking notes. Here is our step-by-step approach to success 😋:
1. Find out the GPU's memory vendor:
Use GPU-Z app to determine the memory type and vendor of your GPU.
- Samsung may clock as high as +700 MHz;
- Microns are capable of around +500 MHz;
- Hynix are the less flexible and stick only with an extra 200-400 MHz.
Given figures apply to NVIDIA Pascal (1000 series) cards. The real boost is highly dependent on a single chip. Carefully increase your clock speeds to find out the value optimal for your particular setup.
2. Live-track GPU's stability:
Launch FurMark stress-testing. This app will generate a load that will test the ability of your GPU to endure an overclock.
3. Boost memory clock:
Use MSI Afterburner to overclock your video card. It has a user-friendly interface and works with any Nvidia or AMD GPU.
Locate the memory clock slider and start to increase the value progressively. Stick with 50 MHz steps.
Monitor GPU load and temperature after every adjustment. At some point, your system will go unstable, and you will experience one of the following symptoms:
- Visual artifacts (random flickers or stripes on the screen);
- Furmark crash;
- "Display driver stopped responding and has recovered" message;
- Screen blackout;
Afterburner does not apply any changes at Windows startup by default. Thus, any destructive changes will be rolled back after the reboot for your safety.
Once recovered, set the memory clock to the last stable value you've noted. For example, the system crashed at +650 MHz, then stick with +600 MHz boost.
4. Test mining stability:
Let your rig mine for at least 24 hours and follow the checklist:
- The rig does not occasionally reboot or freeze;
- GPU load graph is smooth and has no spikes;
- Profitability is stable, there are no $20/mo -> $0.05/mo surges;
- Factual and calculated incomes do not differ.
Excessive overclocking is the most common reason behind unstable mining and overall profitability decreases.
How to reduce power usage of the rig?
It is possible to bring watts usage down with no performance losses!
Pull Power Limit slider down in Afterburner, until profitability or hashrates start to drop. This will limit the GPU's power consumption, making the card to automatically control the core clock and voltage to meet new limits.
Basics of Power Limit
Power Limit is the maximum wattage a GPU is allowed to consume. It is closely related to the card's TDP a.k.a. "How much heat can it generate."
I.e. GTX 1070's TDP is about 150W. Thus, at 100% Power Limit the card consumes 150W.
Power Limit may be adjusted safely. When it is set to the lower values, voltage controller becomes less stressed, power consumption lowers, card cools down. And vice-versa.
Even more aggressive overclocking
AMD Radeon RX 4xx-5xx
Polaris Bios Editor allows you to change memory timings of AMD cards. AtiWinFlash gives a possibility to re-flash the cards' BIOS. Take a look at how to benefit from that here.
NVIDIA GeForce GTX 1080, 1080Ti, Titan X (Pascal), Titan Xp
Use ETHlargement Pill combined with memory clock boost. The effect is pretty solid:
- 35Mh/s at GTX 1080;
- 55Mh/s at GTX 1080Ti;
- up to 65Mh/s with Titan Xp.
Check this article to find more.
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