Archive for the ‘Tests and Reviews’ Category

Nvidia GeForce GTX 1080 and Ethereum Mining, What to Expect

13, Jun 2016

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The new Nvidia GeForce GTX 1080 (Pascal-based) video cards have been available for about two weeks now and we have finally managed to get one GTX 1080 to play around with it and see how good it performs for crypto crurrency mining. We are starting with Ethereum as the currently most popular altcoin for GPU mining and unfortunately the GTX 1080 does not do great for ETH mining. You should already know that Eehereum is better on AMD GPUs than on Nvidia and the new Pascal GPUs such as the GTX 1080 don’t do great either and there are some issues with them on Windows for the moment. The GTX 1080 cards are using faster in terms of clock speed GDDR5X video memory that might do great for gaming, but apparently it does not do great for memory intensive algorithms such as Ethereum. In fact it seems that the GTX 1080 is slower because of the GDDR5X than the GTX 1070 that uses regular GDDR5 video memory, and when you add the high price of the 1080 it is most definitely not good choice for Ethereum mining like it might be for gaming.

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We have compiled a Windows binary of the latest pre-release of Genoil’s ethminer 0.9.41 fork version 1.1.3 (source) with CUDA 8.0 and Compute 6.1 that is used by the new GTX 1080 and GTX 1070 to test with and you can find a download link below. So let us get to the hashrates you can expect from the GTX 1080 by mining under Windows and then from Linux. If you are using Windows 7 or 8.x you will notice that with the default settings the miner will crash when trying to load the DAG file into the video memory of GTX 1080, regardless if you are using OpenCL or CUDA mode. Other OpenCL only miners such as qtminer will also fail with a driver crash, this is a driver issue and even if you manage to not crash the driver you will get a disappointingly low performance. You can run the Genoil CUDA fork of ethminer in CUDA mode with the -U option and add the following parameters --cuda-grid-size 2048 --cuda-block-size 128 to prevent the driver crash, however you will be getting less than 1 MHS in terms of hashrate, so pointless.

gtx-1080-win-10-ethminer

If you move to Windows 10 the situation is slightly better, but not that much actually. With the latest video drivers 368.39 for Windows 10 you will be able to mine Ethereum, unlike on Windows 7/8.x, but the hashrate you will get is still going to be disappointingly low at just about 4-5 MHS. Again a driver issues, however there is a talk about an upcoming driver update that should fix the problem of low hashrate at least for Windows 10 that is expected sometime next month (we cannot confirm this however).

So the only thing that is left to do if you already got a GTX 1080 GPU or more than one and want to mine Ethereum with it is to go for Linux. Under Linux people are reporting about 23 MHS on average as hashrate for mining Ethereum on GTX 1080, a speed that is a bit higher than what you can get from GTX 970, GTX 980 or GTX 980 Ti, but still a bit disappointing compared to what you can get from high-end AMD GPUs. The GTX 1070 that we already mentioned is doing better for Ethereum should be capable of around 27 MHS under Linux (in Windows they apparently have the same low performance issues for the moment), though we have not yet been able to personally verify that. So even with the low power consumption these hashrates from the GTX 1080/1070 are not that great and when you add in the high price of the GPUs at the moment and the driver issues with Windows, you can pretty much forget about being happy with mining Ethereum with these video cards. They should be better capable for other altcoin algorithms that are not memory intensive like Ethereum and we are off to checking that next, so stay tuned for more results.

– To download and try the latest Ethminer 0.9.41-genoil-1.1.3 pre-release for Windows OS…

Modifying KNC Titan Scrypt ASIC With Water Cooling

16, Apr 2016

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After our not so successful experiments in trying to use immersion cooling with mineral oil for the KnCMiner Titan Scrypt ASIC we have moved to trying out different things to make the device run cooler and silent. The obvious next step would be to use water cooling and the options for this are many, so we have decided to start by trying with a pre-filled closed loop All-In-One solution that is ready to be installed just to test out things. We were pleasantly surprised that KNC has decided to use standard mounting holes for 115x Intel sockets on the PCB of the device, so the installation for a water cooling solution designed to support these sockets should not be a problem. The water cooler should be capable of dissipating about 300 Watts of power coming from the Titan ASIC chip (actually four chips in a single package). We have opted out to start with a Silverstone Tundra TD02-SLIM AIO water cooler – dual 120mm slim radiator with two silent slim fans and the results we got with it cooling the ASIC were very good. Using a larger radiator and slightly more powerful fans can help you get even better results temperature wise and still have silent operation, even thicker single 120/140mm radiators could be able to handle things well enough.

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Whatever water cooling solution you go for you need to make sure that the top of the water cooling block is clear, so hat you can place a cooling fan on top of it. The actual problem with the Titan Scrypt ASICs is not the main chip(s), but the DCDC power modules that provide the ASIC with the needed power. The design that KNC has chosen makes it hard to cool them properly and their solution that uses very thick thermal pads is not great either. So if going for water cooling installing the water block is the easy part, keeping the power modules cool is the hard one. In fact you can cool them by just placing a powerful 120/140mm fan on top of the whole thing to blow cold air directly over them…

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Our test with a 140mm Noctua NF-A14 iPPC-3000 PWM fan for cooling the DCDC power modules proved a success in keeping acceptable temperatures, but not in keeping the device silent. The idea to use water cooling instead of the standard water cooling is to make it run cooler and more silent. So the solution would be to do a custom set of heatsinks to fit on the DCDC power modules and have a silent fan blowing on top of them in order to make the cooling efficient and silent enough. Reusing the stock air cooling plate wit the thick thermal pads that the miner comes with will not do well, but it can give you some ideas, just make sure you use thin thermal pads or a thin layer of thermal grease. The end result will be totally worth it in making the KNC Titan run silent and effective especially for home miners with the summer heat not too far away.

The Energy Saver Feature of Gentarkin’s Custom Titan Firmware

12, Apr 2016

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The Energy Saver feature of Gentarkin’s custom KNC Titan firmware was something that we wanted to try out in the 1.0.2 version and we tried to do it, but there was a bug that was causing the process to continue for days without finishing. With the release of the new 1.0.4 version of the custom firmware the issue in the Energy Saver feature has been resolved and we were finally able to finish a complete run on a single Titan Cube in less than 24 hours. On the image above you can see the stock settings of a fully functioning Titan Cube with all cores at 325 MHz with -0.0366V set for each core. The total power usage with these “default” settings is about 347 W and with the PSU power efficiency taken into account it makes it at about 384 Watts with a highly efficient PSU at 92% efficiency, with a less efficient PSU at lets say 85% the power usage will be higher at the wall and the final savings should be more.

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The idea of the Energy Saver feature is to find the optimal lowest operating voltage of each core automatically and test to ensure the miner can run stable at these settings. As a result you get lower power consumption (lower energy bill) and less heat generated by the components, so in theory you should be able to extend the life of your mining hardware as well. All is done automatically and in the end you just need to confirm the settings that are being suggested. Our results for the fully functioning cube set at 325 MHz after the Energy Saver feature was over was an optimized voltage for all four cores at -0.0732V with a slight reduction of operating temperatures of the DCDC power modules. The more important thing is the reduction of the power usage, the actual consumed power by the device went down from about 347W to about 317W or about 30 Watts down, and a total of about 32 Watts lower power consumption at the wall. It may not seem that much, but this is close to about 10% and if you get 30 Watts lower power usage per cube and have a lot of cubes the number and power savings can get quite big. One more reason for users of KNC Titan Scrypt ASIC miners to get Gentarkin’s Custom Titan Firmware.

– Visit the official website for GenTarkin’s Custom KNC Titan Firmware for more info…


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