Testing the 5-chip Gridseed BTC/LTC ASIC in Fanless Cooling Mode

16 Mar
2014

gridseed-5-chip-asic-fanless-power-usage

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?

gridseed-5-chip-asic-fanless-thermal-image

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.



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17 Responses to Testing the 5-chip Gridseed BTC/LTC ASIC in Fanless Cooling Mode

Steven

March 16th, 2014 at 01:50

For any device with a fan that doesn’t already have a fan controller changing speed based on temperatures, go pick up a passive normally open bimetal switch with appropriate temperature rating, and just drop that anywhere on a power line for the fan. Bam, done. Fan off when it’s cool, fan on when it’s hot – takes no energy, takes no interfacing with a microcontroller, takes no fancy control software. Simple, elegant, cheap. Switch bounce may introduce some noise into the circuit, but if that trips up the chip without recovery, it just needs better filtering. Should prevent any accidental gridseed death due to passive cooling with dual/btc mining run.

admin

March 16th, 2014 at 12:08

Steven, thanks for the suggestion, this is also a good idea.

Rowan

March 16th, 2014 at 15:11

Is 2 hours long enough for this kind of test? I wonder if more heat would build up cumulatively over more time (days/months).

admin

March 16th, 2014 at 17:29

Rowan, yes, 2 hours is not enough of course, but can still give a good idea…

We have measured the temperature after 12 hours of use and there is pretty much no change, the variance is within 0.5 degrees C and we expect that in 24 hours there is not going to be much difference either. The massive radiator that these units have can dissipate more then adequately the heat generated from the 5-6W power usage.

jamie

March 16th, 2014 at 20:48

Steven, could you post a link of a switch that could work for this?

Rowan

March 16th, 2014 at 20:51

OK thanks admin for the info. Is there a guide anywhere that shows how to dismantle the gridseed without damaging it? Or is it just a case of taking the screws out of the heatsink and voila, access to the fan wires for the cutting thereof?

admin

March 16th, 2014 at 21:31

Rowan, no need for a guide, it is very easy – just remove the four screws on the bottom, desolder the two fan wires and remove the 4 screws on top under the fan to remove it, then screw back the bottom part and you are ready.

Rowan

March 16th, 2014 at 21:57

Soldering irons don’t like me so I just cut the fan off with some scissors, and taped up the connectors with some electrical tape.

Within an hour the heatsink has gotten noticeably warm.. I guess thats normal..

I assume I am running in low power “Scrypt-only” mode because my bat file looks like this…

cgminer.exe –scrypt -o stratum+tcp://xxxxxxx.com:3333 -u x.1 -p password –gridseed-options=baud=115200,freq=850,chips=5 –hotplug 10
pause

..and I am using this version of cgminer:

http://cryptomining-blog.com/1262-download-cgminer-3-7-2-for-windows-scrypt-mining-on-gridseed-5-chip-gc3355-asics/

If that rings any warning bells please let me know! :)

Rowan

March 16th, 2014 at 22:23

…because there are these two other switches written in the readme file which I perhaps need to additionally specify?

./configure --enable-scrypt --enable-gridseed

admin

March 16th, 2014 at 22:33

Rowan, cutting the wires is also Ok as long as you insulate them, so there is no chance of short circuit. If the miner is slightly war to the touch it is just fine, means it is around 40 degrees. You are using the right command line to start the miner and it is running only in Scrypt mode with this miner. The options for configure are only when compiling the miner to enable Gridseed support, they are not required as you are already using a compiled version of the miner for windows.

Rowan

March 16th, 2014 at 22:48

Thanks admin for the explanations.

Rowan

March 18th, 2014 at 01:50

Seemingly “stable” overclocking to 950mhz (poss 975mhz?) appears possible with a small hardware mod:

https://bitcointalk.org/index.php?topic=519112.20

People are saying it gets a bit hotter, not really surprising. Low speed fan perhaps a good idea in that case.

skuser

March 19th, 2014 at 10:53

Ok so I cutoff fan, removed upper heatsink and this thingie hashes without external power? That means it draws ca 1A from 5V USB, hopefully it won’t burn itdown…

admin

March 19th, 2014 at 11:13

skuser, it may seem to be working with only the USB connected, but it is not actually hashing. You need the external power for the device to actually do some work, so do not leave it connected only with the USB cable!

El Macho

April 3rd, 2014 at 18:52

2 Questions:
(1) Now that it has been a few weeks, has anyone’s 5-chip dualminer burned out? I’d like to run this 24/7 with no fan.

(2) passive normally open bimetal switch <- Has anyone done this? Where can I learn more details on how?

admin

April 3rd, 2014 at 19:59

El Macho no problem running it on the long run fanless (if the ambient temperature is not high – 20-25 Celsius should be fine), unless you decide to voltmod the device to overclock higher. Though we have most of our units voltmodded, original fans desoldered and a single 200mm fan cooling 10 units all at once.

Snaps

May 30th, 2014 at 05:01

Has anyone had any experience removing the fan for volt-modded seeds (~1150mhz and 500kh)? I’ve heard these are sensitive to temps over about 45C.

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