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The summer will soon be upon us and yet again will start causing issues with the cooling of GPU and ASIC miners for a lot of people. This is why we have started doing some experiments with cooling using mineral oil to submerge a miner and using a traditional water cooling hardware for achieving more efficient, silent and problem free cooling during the coming higher temperatures. Out initial experiments have started by using a single KNC Titan CUBE that is submerged in mineral oil, leaving the fan on the miner to move the liquid and using a water pump and a water cooling radiator with 3x 120mm fans attached to it. A simple setup with some water cooling hardware we have lying around unused, but enough to get us started in exploring the DIY mineral oil submerged cooling.
Mineral oil is with different viscosity compared to water, so it is essentially a bit harder to move in a water cooling setup as compared to using water. Also submerging fans in it will make them move at a slower speed due to the increased resistance of the liquid as compared to air, some fans may even be unable to start when submerged in mineral oil. An example of such an issue with the fan not able to start rotating in the liquid is the 140mm Noctua NF-A14 iPPC-3000 PWM fans that are used as a common replacement for the stock KNC fans of the Titan ASIC miners. The biggest advantage of using mineral oil is that it is a dielectric and a good one at that, so it is safe to submerge electronics in it and when everything is surrounded with oil the heat gets easily moved from the components to the oil. When you move the oil through a cooling radiator with the help of a water pump you can keep it cool and thus get a lower operating temperature of hardware that is submerged in it.
What you should be extra careful with is to keep the mineral oil clean, meaning that you need to clean up the hardware well before submerging it in. Introducing dust and other materials could cause potential issues with the liquid moving through the water pump and water radiator and even cause the cooling system to fail if it gets clogged. Another possible problem with other substances getting inside the mineral oil is that they might be conductive and since the oil is being moved around inside the container it is stored in with everything else inside it it may cause short circuit, though that is not very likely, it is still a possibility. Should you decide to takeout the submerged hardware from the mineral oil you will also need to clean it from the residual oil, you should be able to easily do it with alcohol or any cleaning fluid or spray you may have handy and the hardware will look like brand new after that.
Our experiments with trying to cool a KNC Titan cube have shown some interesting results, but it also seems that ASIC miners like that with a single large crystal (or four under one hood) might not be doing that great as ASICs with many smaller chips. In fact we are not seeing much trouble with the ASIC chip itself when it is submerged, we are seeing weird behavior with the DC/DC power units. With normal air cooling the cube is working perfectly fine everything working at 325 MHz, but when submerged some of the eight DCDC power units start to behave weird and restart from time to time. Could be the thick thermal pads used that do not behave well when submerged in mineral oil, we need to do more research on what is causing the problem. Bringing back the Titan cube to air cooling it is working just fine again, so for the moment we are going to move to doing tests with some other mining hardware such as the iBeLink X11 ASIC miner for example that might do better. As for cooling the Titan cube we are going to be looking for other alternatives besides the stock air cooling in the next days as we are not very happy with KNC’s approach.
We have been playing around with a FutureBit MoonLander USB Scrypt ASIC Miner for a few days already and it is time to share our experience with the device. We should start by stating that the FutureBit MoonLander is a small and not very powerful in terms of performance USB miner that is more for fun than for profit. The device is intended for people that just want to play around and experiment with a small and not very powerful Scrypt ASIC that is available at a low price. The miner uses a special version of bfgminer 5.4 (source).
The MoonLander can run on a very wide range of speed and efficiency, allowing the user large headroom for tweaking and playing around. The device comes with a variable resistor on the PCB that allow the user to adjust the core voltage (0.7-1.1V) and a wide range of operating frequencies that can be set via the software (104 MHz to 400 MHz). Of course you need to be careful playing with these as increasing the operating voltage past the default level of about 0.75V and going past 264 MHz would require the usage of powered hub and active cooling for the miner based on our experience. The official information about the miner performance cites a value of 2.77 KHS per 1 MHz, so the lowest frequency should be able to provide about 288 KHS hashrate for mining Scrypt crypto currencies and the maximum of 400 MHz should result in around 1.1 MHs.
With a hashrate in the range 0.288-1.1 MHS for mining Scrypt-basec crypto currencies you will not be able to mine much and you will also have to look for mining pools that offer user adjustable difficulty level or support low fixed difficulty. If we get back a few years to the times of Litecoin mining with GPUs we can say that this miner gets you in between half to almost two high-end GPUs worth of Scrypt hashrate. Of course the power usage of this USB Scrypt ASIC is much lower than what a high-end video card consumes, but then again at these low hashrates you will need many months to even earn enough to cover the cost of the miner. Anyway, our goal was to see what you can get in terms of performance with the FutureBit MoonLander miner by powering the device with a regular USB 2.0 and USB 3.0 ports with their power limits that do not allow the miner to reach its maximum performance. You will need to use a powered USB hub in order to be able to overclock to the maximum the miner, a 2A powered hub should allow you to reach the 10W maximum power and you will also need to provide a serious active cooling to the device if you want to push for higher core voltage and the maximum supported frequency.
Out tests have shown that the default operating frequency of the device set at 144 MHz is what is possible with a USB 2.0 port capable of providing 0.5A at 5V or about 2.5W. With this operating frequency and using the stock core voltage of about 0.75V you can expect to get around 400 KHS worth of Scrypt mining power. On the thermal images above you can see the operating temperatures at these settings, the AlcheMiner ASIC chip does get hot with temperatures of around 55-56 degrees Celsius and the heatsink on the back is at about 44 degrees Celsius. These temperatures should not be a problem for operating the miner without any additional cooling on the long run, unless of course the ambient temperature is not very high.
Going for the higher power limit of USB 3.0 ports that are capable of 0.9A at 5V or about 4.5 Watts of power you can push the device to an operating frequency of 264 MHz. Any higher and the power provided by the USB 3.0 port will not be sufficient enough to keep the miner operating properly. The expected hashrate at these settings should be around 730 KHS, a result that is not bad but we were hoping for a bit more. Apparently achieving 1 MHS or more will be possible only with the use of a powered USB hub that can provide more power to the USB miner and 2A is needed for pushing things to the maximum along with cooling fans as already mentioned. It is important to note that the thermal camera photos show an increase of about 15 degrees for the ASIC chip and about 10 degrees for the cooling radiator when using USB 3.0 as compared to USB 2.0. Note that at this level adding some airflow around the miner is a good idea in order to keep it cooler as otherwise it may overheat after a while, so it will be a wise idea to monitor the operating temperatures.
All in all the FutureBit MoonLander USB Scrypt ASIC miner is a fun little gadget to play around with and that is what it is for – playing around with an affordable ASIC miner. It is not intended to be profitable or to make you a lot of money, it is for people that are curious like us and love to play around with tech. The next thing we are probably going to do with the device is to improve on cooling and try with powered USB hub and some overvolting and more serious overclocking of the device. Do note that increasing the operating voltage and trying to max out the operating frequency can decrease the live of the mining hardware and even damage it permanently if you are not careful what you are doing!
– For more information about the FutureBit MoonLander USB Scrypt ASIC miner…
- In: Mining Hardware|Tests and Reviews
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The iBeLink DM384M is the first to market X11 ASIC miner and while it is a pretty good product, there are still some things to be desired. In terms of hardware the X11 ASIC miner offers a solid build and reliable performance making it pretty capable for mining in a data center even in not so favorable conditions even when the environment temperature is not the best. The power usage is at a good level for the high performance it offers of 384 MHS for X11 mining, but the noise level makes it inappropriate for home miners. Temperature wise the situation is good thanks to the powerful server grade cooling used to keep the miner operating stable as you can see from these thermal images of the device in operation. Pretty much what is missing in terms of hardware is the presence of thermal sensors and fan control available for the users, the first is not hard to implement considering that the built-in controller of the miner is a Raspberry Pi. Fan speed control and failsafe could be trickier to implement as it would also need to be able to ignore users settings if the conditions require it and even to shutdown the miner in case a fan fails. Not to mention that implementing fan speed control and monitoring would not be very usable without the miner having thermal sensors, but the current implementation with server grade fans is good enough and should provide long and reliable operating with adequate cooling.
On the software side however there is much more to be desired, even though the basic web-based functionality you get is a pretty good starting point. we have already mentioned the device uses a Raspberry Pi controller with a modified version of the MineNinja software to provide a web-based frontend to the cgminer 3.5.6 backend. The web frontend provides a lot of numbers to the users, but they do not always seem to be correct, especially in terms of the actual hashrate you are getting from the device, so you need to look at the pool reported speed. Furthermore the web-based control lacks some very basic features such as password protection for access control or the ability to use a different pool mining strategy than the default failsafe one that is available. With big and powerful ASIC miners we often see that the web-based control software offers only pool failsafe options, but no load balance strategy for example. So while this will be fine if you are mining a high difficulty coin, if you go for a low difficulty and hashrate one throwing your full hashrate you will quickly raise the coin difficulty a lot. The cgminer backend does come with support for different pool strategies, so the problem is in the functionality available in web-based interface. Unfortunately for the moment the source code of cgminer or at lest the driver for the device is not yet publicly released, so we cannot have support built in other miners and web frontends. So for the moment the iBeLink DM384M is best for use with high difficulty X11 coins…