Computer cases are sold with obsolete fans. Protest. Rip the fan out and post it back to the manufacturer claiming a refund for that part of the case cost.
PWM is what you need. Manufacturers are still delivering cases with inferior substitutes.
I purchased a brand new Antec case and the fan in the back of the case is an ancient fixed speed fan, the same as was used in the 1960s. Your grandmother would recognise it.
The manufacturers have moved up from the old 90 millimetre fans to modern 120 mm but nothing else has changed. Some still use sleeved fans instead of ball bearings or floating fans, a category of bearing that is a sleeve but is continuously self lubricating.
The Antec fan had a two speed switch, useless because the slow speed is not slow enough to be quiet and does not automatically speed up to fit the cooling requirement.