Cooling for the MiSTer FPGA is important, the DE-10 Nano’s system on chip integrates a hybrid 800MHz Dual-core ARM Cortex-A9 processor and an Intel Cyclone V SE FPGA. The main source of heat is the integrated Dual-core ARM which produces a constant heat regardless of the FPGA use. At the bare minimum the MiSTer FPGA needs a passive cooling solution, this is accomplished by adding a high quality heatsink. However for long term use an active cooling solution paired with a heatsink is highly recommended this is achieved by also adding a 40mm fan.