Just found this thread. Having recently bought an RPi5 for Zynthian experiments, this looks very exciting. Not to put down the V5, put there’s something nice and compact about the V4 so an RPi 5 upgrade appeals to me.
I recently bought an RPi5 with a passive cooler, which basically is a large block on the top which has thermal pads to the CPU and other chips. It looks more or less the same as the one that @spacedentist used in this thread. There is a cooler on the back too, which doesn’t have any thermal connection except via the screws.
I did a quick test connecting the RPi5 to the hardware and configuring it appropriately, just to see that everything played nicely together. The RPi5 is a tight fit when squashed sideways on top of the existing RPi4 but it worked well enough for testing.
Looking at the connectors, in terms of Zynthian, the only difference is that the USB and Ethernet ports are swapped, which will require a bit of operation (filing) on the case, and that there is no headphone output. The USB-C and HDMI connectors seem to be in the same place. So not a lot of work is needed on the case, really, it seems.
My plan is to remove the bottom cooler (because with it the RPi5 will sit too high in the case to match the holes for the connectors), and instead mount it like the RPi4 is mounted, on metal standoffs, which should transfer some of the head via the screws directly to the bottom of the case. The audio card needs to be mounted on an extender, and I’ve verified that even with an extender it is not too high up in the case - the audio board connector is the highest point, and it fits just under the Zynscreen.
There is the issue of how to anchor the analog board. Either drill holes in the headsink and use standoffs, or put small angle brackets against the back of the V4 case. I’m not really happy with letting it just sit on the connector.
Another option for increasing the cooling is to bolt the heatsink to the back of the V4 case using a couple of screws.
The question is if this will be enough in terms of cooling. My gut feeling is that it will be, especially since the case is fairly well ventilated. Opinions? @spacedentist @niels - Does the passive seem to be sufficient in the long run?