V4 - consider placing fan instead of the cutout under FMC
The cutout under the FMC is in many cases insufficient to cool the mezzanine. We designed a custom fan for the SPEC (see https://www.ohwr.org/project/fmc-delay-1ns-8cha/wikis/Heatsinks). A future version of the SPEC could support mounting an off-the-shelf fan instead of additional PCB under the FMC.