Its possible spaghetti code doesn't like more than 2 fans plugged into the controller.
doggie- do not write another BS comment.
I have eight double size S7 and they all show four fan speeds.
FAN 40%
Dual S7 miners
3,240 3,120 3,120 3,120
3,240 3,120 3,120 3,120
3,120 3,000 3,120 3,120
3,120 3,120 3,120 3,120
3,120 3,120 3,120 3,120