Archive for the ‘Mining Hardware’ Category


It seems that the community has figured out a way to do a voltage mod for the Gridseed 5-chip ASICs that allows for higher overclock frequencies and thus even higher hashrate. We have decided to try out the mod ourselves and report our own findings and results with our older and newer dual mining mode ASIC devices from Gridseed. What you need to do in terms of hardware modification to your miner is to solder a bridge on the place marked with the green line on the photo above. Then you need to run the latest version of the modified cgminer for Gridseed with an extra option for the gridseed options line “voltage=1”. Note that the space where you need to solder a bridge is very small, it is designed for SMD resistors and if you are not experienced with a soldering iron you will have trouble performing this modification by yourself. Also if you are not very careful you may damage the device by soldering something that should not be soldered and thus shorting the ASIC, so be very careful should you decide to mod the device or higher voltage!


After performing the hardware modification to our two miners that are from different revisions apparently we have tried running them with the modified cgminer (download link for the windows binary below, for the source). The older revision of the device we’ve got with CP2102 USB to UART Bridge Controller trying to run the setting to set the higher voltage from within cgminer returns an error about the firmware not supported. The device has a firmware version 01140116 and apparently this version is not supported, even modifying the cgminer to recognize it as supported firmware did not help in being able to overvolt and overclock the miner. The other newer ASIC device with STM32 Virtual COM port driver was with the correct firmware version 01140113 and the miner apparently did activate the overclock and overvolt mode. The power consumption of the device we have measure with the voltmod and running at 950 MHz frequency was with about 2W higher than at 850 without the voltmod, or with other words 8W instead of 6W (in fanless mode) with 2W more with the fan working (10W and 8W respectively). If you are doing the voltmod however we would not recommend to use the device in passive fanless cooling mode, though at 850 MHz and with no voltmod we have been running a single miner for already 48 hours without any issues.


With the increased voltage of the Gridchip GC3355 processors we were able to get from 850 MHz with no or very few HW errors (361 KHS) to 950 MHz with no to very little HW errors (404 KHS) after the modification. We could also go to about 425 KHS at 1000 MHz with very few HW errors, going up to 1050 MHz produces almost 450 KHS, however the number of HW errors we are getting at that frequency is significant, so the real performance is probably much lower than at lower clock speeds. What we would recommend as the most stable result is to go to 950 MHz as overclock frequency as good starting point after doing the voltmod and go up in 50 MHz steps to see how will your miners perform at higher frequencies and if they will do any better results. The latest version of cgminer supports overclock up to 1300 MHz in 50 MHz steps, so you can go pretty high, though you should be careful as the increased voltage and frequency might lead to damage of the device.

You can download cgminer 3.7.2 for Scrypt mining on Gridseed 5-chip GC3355 ASICs on Windows OS here…


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.