Bitcoin Forum

Hi All

I have just been given an S9 that would not run, exhaust fan was faulty.

I then went to reconnect it and it was attached inside port/socket of the two?

I then checked all my miners and around 10% have the input to outside socket/output to the inside socket?

I have always gone by inside/=input, outtake=outside.

Am i missing something here? Or does it not matter as i have both and all have been running for months.

Cheers

In their infinite wisdom I don't think Bitmain ever came close to a standard fan assignment. What fan plugs into which controller fan socket varies between the batches. All that matters is that whatever sockets that batch look at get feedback from the fans.

I agree, useless company, they don't care as they know they won't get returns...Ah well.

Fans show varying speeds when connected either way BUT temps are definable lower with intake/inside, exhaust/outer.

Yes because normally one is slower than the other (ie 4k vs 6k rpm). But you could just use two 6k fans and it won't mind. Connector position is really unimportant.

So which output gives the lower PWM to create the neg pressure, obviously two 6k fans would be different as the outputs are telling.

The newer models use lower amperage fans on the intake but same speed. RPM to Wattage ratio to save power seems the only logical answer.

This is just my guess, but i think it occurs physically, not logically. By having one weaker than the other, it creates the difference. The controller is probably just sending the same thing, if you send 80% to a 4k, this results in 3.2k, but to a 6k fan it is 4.8k. Think Chinese way, cheap, make it cheaper. Control them separately? no way, that's double the effort and costs (and remember the controller actually has more, you can solder the plugs back and they all work), plug any two fans in any position and the firmware is happy You can probably use more than two, but i have no idea what is the current load limit of the poor thing.

With both being 6k but one with thinner blades than the other, i guess you get the same result with numbers looking prettier. Main reason to do that would be to save some cents with the cheaper fan motor.

I wonder how is that done with S17 4 fan configuration... Two strong and two weak?

You get negative pressure as long as your exhaust wants to move more cfm than your intake, however you do that doesn't matter. What happens if you get equal pressure? Probably nothing bad, you just are using a more expensive (and noisier) fan in the intake.

But be my guest and experiment swapping the plugs, i doubt you'll notice any difference except in the web UI fan number.