Hi all, I'm a first time poster and a new miner so you may take this with a grain of salt.  The D3 was the first mining rig I purchased so I have been extra cautious as I begin my mining.  I have done a lot of looking and here is what I have noticed and found.

I submitted a ticket to vitamin technical support which I will copy and paste below.

What is the optimal chip temperature for the D3? I have a Nov. batch D3 (19.5Gh) and the chips are operating around 80. I know there is a shutoff at 85 that will give a fatal error due to high temperatures. I was getting a decent amount of failures, so I lowered the frequency. I'm getting about 17Gh now, but no errors. I don't want to shorten the life of the miner by running the chips too hot. What temperature are the chips designed to run optimally?

Also, the miners are indoors, in a climate controlled environment with ambient temp kept at 18-20. Cooling fans are on automatic running from 4500-5000 RPM. Thanks

This was their response:

Dear Dustsam15,

Thanks for your consultation!

the chips are operating around 35-80. so a little high is ok.
Please lower the D3 frequency to 487.
fans are  running from 4300-6000 RPM.

Please let us know if you have additional questions or concerns.


Best regards,
Maria
Bitmain


So it sounds to me like 80 is the max acceptable temp. for the chips.  I am trying to keep mine closer to 70 since that's still the high end and I want my miners to last.

I have also looked at a ton of D3 review and tutorial video to try to get a peak at what temp other peoples machines are running to get some sense of "normal" and it seems the 19.3GH versions are running pretty hot.  it's very common to see them in the high 70's with one board in the low 80's.  I think that bitmain just overclocked the 15Gh version as the profitability declined.  I have under clocked my miners from 15-17GH depending on how they run individually.