I was lucky, I got 4 fan Delta ;DTFC1212DE-SP07 for $ 36 including shipping
thats the fan i got to pair up to the stock fan, it flows alot of air.
the fan i got tho was reversed pwm, so i had to make an adapter.
Sure you get long enough wires??.... the ones on S5's connect to the PCB instead of the HashBoards.
Lot greater travel distance for the wire to connect.
Back then the S1 & S3 fans were interchangeable, the S5 killed that.
The difference is about 2 inches in wire length.
You may need to get your hands dirty or buy the fans directly from Bitmain.
Soldering's no big deal but was kind of stupid to omit the hashboard fan connectors.
Just hope they are long enough, then I'll know what to hunt.
Those 4,000 CFM fans ain't cheap, let alone with enough rope...
the wires were perfect length..
the fan i got use a reverse pwm signal. so instead of 0v full speed, and 5v stop, its 0v stop and 5v full speed..
im not sure if the fans he got are the same.