[selcuka]

> It's surprising that there are no PC fan controllers that would use some variant of PID control with a temperature target.

They actually exist (such as ARCTIC F12 TC) but not very common. Separate controllers such as Adafruit EMC2101 are also available.

[4gotunameagain]

Both EMC2101 and F12 TC work with a look up table, so a normal curve as opposed to a PID.

You can verify that in the datasheet of EMC2101, and in the case of F12 TC in product descriptions (..The fan responses to the rise in temperature swiftly – within a critical 6°C range, the rpm of the ARCTIC F Pro TC fan increases from around 500 to its maximum of 2,000 rpm (the steep curve in the chart).)