I nearly freaked out mine are getting 38 degrees Celsius. So close to 40.

Now i‘m relaxed after I hear how high they work fine.

Room temp is around 30 - 31 degrees.

Miner at 70% fan speed (more speed changed not many, but reduce lifecycle)

I keep humidity below 50% (important!) and above 30%.

Dust filters keep them clean, so I think i‘m good to go.