Now, the manual for the HBA you were talking about states "Minimum airflow: 200 linear feet per minute at 55 °C inlet temperature"... ...which is the same as my RAID card.
Beyond that, all I can say is that, even with water cooling the CPU & GPU (& an external rad) so most of the heat's already taken out of the case/ the case fans are primarily cooling the mobo, memory, etc, then I've had issues without direct cooling with all of my previous LSI RAID cards - both in terms of drives dropping out & BSODs without there being an exceptional disk usage.
(it's not that I'm running huge R50 arrays or something - primarily that I simply prefer using a RAID card, vs a HBA, in terms of the cache & BBU options)
Similarly, the Chenbro expander I have - which, other than the fans, drives, cables, MOLEX-to-PCIE (to power the card) & PSU, is the only thing in the server case - came with a fan attached which failed; & again I had issues... ...so it's now got one of the Noctua fans on instead.
So, whilst you 'could' try it without & see, personally I would always stick a fan on something like this.
I couldn't advise you on monitoring for PWM as that's not how I do things - since I'd far rather have the system being stable irrespective of whether or not I was in a particular OS or not.
Well, not that dissimilarly, whilst the rad fans are PWM, for me it's about creating a temp curve within the bios for the CPU (& hence, by default, the GPU), & so is entirely OS independent.
So, whilst I couldn't recommend anything specific, 'if' I were looking for a fan controller then I'd want something which I could connect a thermal sensor to (& attach that to the h/s above the IOC) AND I could set the temp limit solely with the controller.