The above gear is Whatsminer M21s 54TH, it has been mining since Oct 2019 nonstop, never been cleaned or looked after, it was put under extreme conditions of outside temperature as high as 45c, recently and for the past 30-40 days the rear fan died and the miner did NOT stop hashing, yes, it did not (not sure why MicroBT firmware does not care about 1 out of 2 fans going down).
The backside of the miner was almost boiling, it was too hot to touch, we literally had to let it sit there for a few mins before we could hold it, no Bitmain gear would endure that much except for the old and gold S9s.
As you can see in the image some of the heatsinks were literally blocked, but with zero problems, even by the look of it and without having to be an expert you can see that these gears are more robust than Bitmain's by a huge shot.
Surfing the Chinese market, you get to find a ton of used Bitmain gears but it's very hard to get your hands on Whatsminer, looks like the Chinese have figured this much already long, long time ago.
Comparing the M21s to the 17 series of Bitmain, the winner is obvious, I am pretty sure if an S17 was as dusty and ran with only 50% of its fans, it would have died in no time.
