this ? CoolJag BUF-E
there is one at ebay(used, from spain 32+7eur)Especially the Noctua nh-d9l build (a bit pricy, and Aliexpress link not available anymore)
50C isn't hot at all for a modern CPU. Intel recommends a maximum of 80C for these CPUs and I wouldn't worry about running them at that temperature for a decade if necessary.I've been running TrueNAS on a X10SDV-4c-TLN4F in a Node 304 with six disks for the past 5 years. I am one those, who stuck a 60mm Noctua with those rubber thingys on the stock heatsink. The temps, or rather the fan load always has been rather high: a perl script controlls the cpu temp to be 50C, which results in about 2800RPM of the fan with normal operation, so not a lot of margin.
In the near future, I will need to move my NAS to a much more enclosed location, and I am afraid that the temps will rise above 50, which is already quite high.