Quote from: Captain-Karacho on November 18, 2015, 01:39:02 PM

Hey Guys,

one of my 3 C1s is not functioning normally anymore.
It started about one week ago, when I noticed that the fan of this particular miner was running at full speed and I was not able to access it via the web interface. Shutting the device on and off resulted in the same issue: fan starts and continues to run at full speed, no accees to the device.
Since also the hard-reset did not work, I took out the SD-Card and flashed the Stock Rom from dogie. After inserting the SD-Card back into the C1, I was again able to access it and everything looked normal. I then flashed the most recent firmware from Bitmain and started mining at 250Mhz/ 0.760.

However after a few minutes, the temperatures of Chain 4 first started dropping and then increasing to up to 125°C, with the fan running at full speed, causing the C1 to stop mining. Guess the temperature reading is not correct since the heatsinks (I currently am operating the device without the case) don't feel hot at all. After shutting off the miner, waiting for a few minutes and then turning it on again it starts hashing again for a while before the whole issue starts over again.
After doing a software reboot while the fans are running at full speed, I noticed that Chain 4 only shows 15 instead of 16 ASICS. Still fans continue to run at full speed and no hashing. Furthermore the Load Average is far smaller than the one from my two other C1s.

In short:
Hashing --> Temperature of Chain 4 drops --> Temperature of Chain 4 increases --> Fan starts running at full speed --> Miner stops mining (and the status light starts blinking red)

What I have tried so far:
- flashing the bitmain firmware (dec 14) again
- trying different frequencies and voltages
- adding PCI-E cables to make sure it's not the PSU
- connecting the radiator and the fans to another Chain
- trying to start the miner without Chain 4 by disconnecting the cables (but it won't start)

Did anyone here experience something similar before? Any idea how to solve this problem?

One more thing: can I pull out the PCI-E (6-Pin) cable connected to Chain 4 while the Miner is runnning or do I risk damaging the hardware doing that?

10m

20m

40m

Load

Every help greatly appreciated

I think you've running your C1 at too high a voltage & frequency, 250@0.076 is in my view a tad too high. Certainly, other people have run their C1's at that speed with no permanent damage, but other C1's have suffered damage, BMT's quality control sucks egss, you know. I found my C1 runs cooler and more reliably at 200@0.070, it hashes at 800 GHs, not a problem since I'd like mine to last a while longer.