Just got my GDemu after waiting months watching for the preorders to be open for less than 24 hours and wait a couple more months to get it. Totally worth it! XD

Also found this little fan and heatsink on an old cheap low end nvidia graphics card that fit Perfectly alongside the gdemu. I've seen other mods out there putting heatsinks and/or additional fans to help cooling, especially the power supply gets fairly hot.
This provides great airflow over to the psu and right under the gdemu across the cooling plate. pins plugged into the 5v power. This fan will go up to 12v but its plenty fast and quiet at 5v. I also swapped out the stock fan in here with one from another of my dreamcasts that is practically silent. All 5 of my dreamcasts have had all different parts from different manufacturers 3 of the fans are fairly noisy and this one is silent and seems to move enough air.

There is no hard modding and this is NOT permanent it can be easily removed at any time. A bit of thermal paste underneath and a bit of hot glue on each side to hold it but will easily pop off.

It looks too close but there's enough room for everything. at least a mm of room everywhere and nothing is touching the gdemu and its not too close to hit the sd card but i will not remove it while its turned on to be safe.
I trimmed away the plastic on that side to provide more space and airflow underneath. It fit perfectly and even a screwhole on the heatsink fit right where that little nub for the gd drive by the screw is so it sits perfectly flat on the plate. Like it was mean to be lol
Check it out!
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If I were ever going to do more Hard modding like overclocking I would cut away a the plate underneath and put the heatsink and fan right onto the cpu and gpu.