Why does 2 same S9 models at same location have 2 different temperatures??

[Sandal_Hat]

Antminer S9 13.15 TH -


Antminer S9 13.15 TH -



I dont understand it. Both are 13.5 TH miners. They are located next to each other on a shelf. However, they have different temperatures.
And the oddest part is that the chip with the lower temperature on the miner have lower HW errors.

Why? 

[Emoclaw]

It'd be logical to assume that this is due to silicon lottery. The hotter chip most likely needs more voltage to achieve the same level of performance and thus it came like this out of the factory.
QC at Bitmain isn't that great so it's normal for them to let allow for such large variations. It happens. You probably shouldn't worry about it, unless of course it gets too hot.

[Sandal_Hat]

It'd be logical to assume that this is due to silicon lottery. The hotter chip most likely needs more voltage to achieve the same level of performance and thus it came like this out of the factory.
QC at Bitmain isn't that great so it's normal for them to let allow for such large variations. It happens. You probably shouldn't worry about it, unless of course it gets too hot.

Hmmm i see. I guess there is no way for me to improve on this

And your idea of too hot is above 90 degrees or 100?

[leowonderful]

In addition the application of the thermal epoxy might be different or whatever thermal compound they put on their chips nowadays. Temps look okay the way they are so I wouldn’t worry too much about them. I remember having to repaste miners in the past and using up a whole tube of good quality paste because the paste on older Bitmain miners weren’t applied very well.

Below 90 is a good goal to reach for you. Under 70/80 is actually preferred, you might want to consider switching your mining area or adding more airflow to the miners.

[fanatic26]

These machines will run safely for months at 100c chip temps, you have nothing to worry about.

[Sandal_Hat]

These machines will run safely for months at 100c chip temps, you have nothing to worry about.

Noted. Thanks

In addition the application of the thermal epoxy might be different or whatever thermal compound they put on their chips nowadays. Temps look okay the way they are so I wouldn’t worry too much about them. I remember having to repaste miners in the past and using up a whole tube of good quality paste because the paste on older Bitmain miners weren’t applied very well.

Below 90 is a good goal to reach for you. Under 70/80 is actually preferred, you might want to consider switching your mining area or adding more airflow to the miners.

I accidentally broke one of the fans on one of the antsminers S9. I cant remember which one and I replaced it with a bitmain fan.
U think it could be that?

The thing is the miners are next to each other. Air flow is the same. I could switch locations but I believe would be the same.

It seems the front and back fans of the hotter miner tend to have the same RPM and the fans on the cooler miner always have higher RPM for fan 6, which i think is the back fan.
So, it is running cooler because of negative pressure?