Review:
Hardware:
The unit looks well build. Missing from this review model is the housing, which it is missing for sure. The ASIC chips closest to the fan are at least 15 degrees C cooler than the chips at the other end of the board. Simply because their hardly any airflow over them.
The heat sink on the board is not the ordinary straight one, but has round shaped fins for a little bit more area, so a bit better cooling. The fan speed is controlled, and at times revs to 5500rpm. According to
http://www.nmbtc.com/fans/part-numbers/DC-Axial/4715KL-04W-B56/5267 the air flow is up to 130CFM, so rather high for a 12cm fan.
Temperature of the heat sink is between 35oC and 43oC, again without casing. Overall the temperature varies between 40oC and 60oC depending on the part and place on the board relative to the fan. (I got all temps with an infrared thermometer).
The PCB itself looks very clean and neat. I viewed it under a magnifying glass and am impressed by the quality. All soldering joints are neat, all components are straight on the board and the four parts of the board are screwed to the heat sink with 20 screws.
I had to disconnect and connect the power a few times while viewing the unit from all sides. It seems rather sensitive to vibration and is best left alone once installed.
The asic chips run on a frequency of 350Mhz and this doesn’t seem to change. The fan is throttling for extra cooling if needed. There is one temperature shown on the miner status webpage.
The unit is easy to disassemble, it has two plates, two connecting rods between the plates and the heat sink is also screwed against the two plates, making it a sturdy construction.
According to my Corsair AX1200i, the unit uses ~17A @ 12V (~204W) and produces around ~85GH/s according to Btcguild. This calculates to ~2.4W / GH/s.
Verdict: Pretty good for a first product!
Software:
The unit is running a modified version of OpenWrt Barrier Breaker r38031 / LuCi Trunk (svn-r9909) running on a TP-Link TL-WR743N/NB v2.
The unit has to work hard, after login in with ssh, top showed 90%-100% cpu for cgminer most of the time. I was running the unit over wifi, but doubt if this has anything to do with it.
The cgminer version on this unit is 3.4.3, the command running is cgminer —-lowmem —bitmain-options 115200:32:8:40:350:4d81 -G -o stratum+tcp://eu-stratum.btcguild.com:3333 …
Since the unit has 64Gb of ram, of which less than 50% is used, I removed the —lowmem, and at a first glance this seems to make it run a bit smoother(CPU: usr 60%, sys 40% versus usr 40%, sys 60%) and a higher hash rate(5+ GH/s, but again by running for a few minutes). This has to be tested better than just for a few minutes. There certainly is room for improvement here, given the amount of free memory.
Every 3 minutes cgminer-monitor is executed. The monitor checks three things. Is cgminer running, has their been newer „Last valid work” and is the miner count not blank. If either of the three checks fails, it kills cgminer and restarts it.
The web interface looks a lot like the Avalon software, so I had no trouble finding my way. At first the pages loaded slow and sluggish, but after removing the lowmem option from cgminer the loading went a lot faster.
There is room for 3 pool specifications on the miner configuration screen. There is bio field yet for extra cgminer options, nor to change the ASIC speed. This can be done via ssh, by modifying the file /etc/init.d/cgminer, but should be available via the web interface too.
Backup/Flash firmware is available via the web, but I haven’t seen new versions yet.
While browsing through the web pages I now and then see some XML parsing errors, but they disappear within a second. I searched through the logfiles available, but there were no XML messages in it. (NO, not by hand, but: # grep -i xml `find / -name '*log*' -print`)
This should be enough text for now, feel free to ask questions and I’ll answer them tomorrow CET.
Edit: After receiving comments on it, I have to confirm that the relation I wrote above between --lowmem and a higher hash rate is incorrect. Me looking at the top screen while writing the review at the correct/wrong moments, take your pick.
I stand corrected, hence this edit of the review.
