All About BTC, LTC, ETH mining as well as other alternative crypto currencies
When we’ve made our previous guide for dual mining BTC and LTC on a Gridseed 5-chip GC3355 ASIC we’ve only had an earlier revision of the miner that used CP2102 USB to UART Bridge Controller. Now that we already have a newer revision with the STMicroelectronics Virtual COM Port we have decided to update the guide with information on how to Dualmine on these ASIC devices. Note that we do not recommend using these devices for dual mining mode, but for Scrypt only mode instead, but you are free to decide for yourself. The advantages of using Scrypt only mode are the low power consumption and heat, the ability to overclock higher, including with a voltage modification and a choice of multiple more up to date software miners. Note that the only way for the moment to use the Dual Mining mode on the Gridseed 5-chip GC3355 ASIC devices is to use the special version of cgminer 3.8.5 for BTC mining (SHA-256) along with the special modified version of cpuminer for Gridseed for LTC mining. Due to the way that the Dual Mining mode is realized on these ASICs using a more recent version of cgminer or bfgminer for LTC (Scrypt) mining on these devices along with the cgminer for BTC mining is not possible at the moment.
– Open up Windows Device Manager and go to the Ports (COM & LPT) and note the COM port that is written behind the STMicroelectronics Virtual COM Port driver
– Download and run the latest version of Zadig
– From the Zadig interface select Options and choose List All Devices
– From the Dropdown list of devices select STM32 Virtual COM Port and click on Replace Driver with the WinUSB driver selected
– Download the dualmining package that we have prepared for windows that contains cgminer 3.8.5 for BTC mining and cpuminer for LTC mining
– Edit the BAT files for the two software miners included in the archive with your settings for BTC and LTC mining pools
– In the LTC-START.bat file you will see an option “gc3355=\\.\COM4”, here you need to change the COM port number to the one you have seen in the device manager before updating the driver with Zadig to use WinUSB
– First you need to start cgminer 3.8.5 for BTC mining, wait a few seconds until the software starts up and connects to the pool and starts working
– Then start the cpuminer for LTC mining, note that you will need to wait for some more time here before the miner connects and starts working, but it it takes more than a minute maybe something is not right
If you still haven’t used cpuminer for Gridseed you should know that the software does not report local hashrate, so the zeroes you see are normal, it is actually working and sending shares. Also note that when in Dual Mining mode you will not be able to overclock the device as high as when only in Scrypt mining mode, so it is normal to be getting lower hasrate. As we’ve already said, we do not recommend the Dual Mining mode and suggest to use these ASIC devices for Scrypt mining mode only, especially if you want to run multiple devices.
If you are using the 5-chip Gridseed ASIC devices in Scrypt only mining mode you probably already know that they are using about 8W of power when overclocked. But what about optimizing the power usage even more by removing the noisy fan that might be needed for the 60W power usage in Dual mode or the 50 and something in BTC only mode, but you can go without it in Scrypt only mode. So we did just that, desoldered the fan from the ASIC and ran the device in fanless mode. And surprise, surprise the total power usage without the fan gets down to just about 5-6W overclocked to 850 MHz, but what about cooling without a fan?
Running for more than 2 hours already the ASIC in fanless mode mining Scrypt has shown that it can do just fine with passive cooling. The maximum temperature was about 36.6 degrees Celsius at the hottest point with an ambient temperature of about 25 degrees Celsius. Don’t get the wrong impression from the thermal images, these temperatures for passive cooling are more than adequate and essentially the cooling radiator is considered cool, meaning that in Scrypt only mining mode you can do just fine with passive cooling at lower ambient temperatures. If you have multiple units together you might want to have a single big fan with slow rpm just to move a bit of air around them you you can be safe even when the summer heat hits.
A word of warning though, if you remove the fan from the Gridseed 5-chip ASIC devices and for some reason you start a miner for Scrypt that does not stop the BTC mining part or you start the dual mining mode you will have trouble with cooling the device and this can lead to a damage of the ASIC caused by overheating of the chips – most likely the first to blow up would be the voltage regulators. So be careful that you run only in Scrypt mode if going fanless and to use miners that do activate only the Scrypt mining mode and disable the SHA-256 one.
Today we have decided to compare the Gridseed 5-chip BTC/LTC Dual Mode ASIC devices in terms of thermal characteristics when operating in Scrypt only mining mode (~8W overclocked) and in Scrypt/SHA-256 dual mining mode (~65W overclocked). We wanted to see how good the massive radiator and high-speed cooling fan will be able to handle in the two modes and more specifically in the dual mode as it is apparently designed to cool the device properly with the high power consumption that it has when mining for BTC (SHA-256) and LTC (Scrypt) at the same time. So we put two ASIC devices next to each other, the one on the left is running in Scrypt only mining mode and the one on the right in Dual mode mining for BTC and LTC at the same time.
We left the devices to work for an hour before taking the thermal images in order to see what are the temperatures of the two miners. Note that the top of the devices does not seem very hot and the highest temperature is that of the cooling fan’s motor. You can however see that around the device running in Dual mode the temperature is higher due to the hot air that is being blown. Looking at the bottom part of the device however we can see more serious difference in the operating temperatures of the two devices. The highest temperature of the device mining in Scrypt only mode we measured is 32.1 degrees Celsius, the device in Dual mode on the right however shows very different results – the maximum temperature we have measured was 73.5 degrees Celsius. As expected the highest temperature measured is at the part where the 3 voltage regulators are located and while they are probably rated to work at temperatures of up to 100-120 degrees C they still do get quite hot as they do not have direct contact with the cooling radiator of the device. So if you plan on running the Gridseed 5-chip BTC/LTC ASIC in Dual mode you might want to consider adding additional small radiators for problem free operation in the long run. The maximum temperature of the Dual mode ASIC aside from the voltage regulator’s region was 44 degrees Celsius, so the cooling of the Gridseed GC3355 chips is more than adequate.
What we would recommend however if you are getting Gridseed 5-chip BTC/LTC Dual Mode ASIC devices is to stick to running them in Scrypt only mining mode where their real advantage is – high performance Scrypt mining hashrate with very low power usage… and no potential problems with the cooling either. Next up we are going to desolder the fan of the Gridseed ASIC devices to see how they will be handling passive cooling in Scrypt only mining mode.