Looks like you need a better heat spreader, not a fancy fan. Roll a copper or aluminum plate into the core housing, keep it flush with the joints. Add a thin layer of graphite between the plate and the core to shunt the heat out fast. If you still need to move air, run a few low‑power blowers right at the vents, but keep them tiny. The trick is to let the heat do the work, not the system. Stick to solid conduction, no extra mass.