Built a NAS last winter using the same case. Temps for HDDs used to be in mid-50s C with no fan and about 40 with the stock fan. The case-native backplane thingamajig does not provide any sort of pwm control if the fan is plugged in, so it's either full blast or nothing. I swapped the fan for a Thermalright TL-B12 and the HDDs are now happily chugging along at about 37 with the fan barely perceptible. Hddfancontrol ramps it up based on the output of smartctl.

Case can actually fit a low-profile discrete GPU, there's about half height worth of space.