How much ventilation do cases need?

The 2-piece cases do have some ventililation, and it seems to be adequate - I have 4 of them mounted on the backs of monitors. Using them in the sun didn't exhibit any problems, even with direct heatr from the sun and indirect heat from the monitors.

Mobile phones use ARM CPUs, and don't have any ventilation. The GPU in the pi runs hotter.

the odd thing is that the answer is 'surprisingly little'

I used to design audio kit and some of the stuff we did was in 1U steel boxes so it could be rack mounted fr studio and disco type use. Things like electronic crossovers were only a few watts, but they would overheat..until I specified a couple of slots in the metal case - very small area in total, but it was just enough to allow air to get in and out and convection did the rest.

so you only really need a few 3mm holes drilled in the case and most people don't bother - I suspect the connectors themselves allow enough air in and out.

Only a hermetically sealed box is going to be a potential issue

So far I've only bought one RPi, which lives in a Wafer case,

However, since this RPi is intended for hw and sw development I wanted a case that allows access to all connectors etc while still preventing screwdrivers etc being dropped onto the PCB or it getting shorts by putting the pi down on a workbench. I wasn't thinking about cooling at all when I went for it, though of course its ventilation is quite good.

I have a digital camera in a diving case. If I use it heavily then open the case it is pretty hot.

You don't need ventilation. I have one in a "closed" Cyntech case,

Temperature in millicelsius:

cat /sys/class/thermal/thermal_zone0/temp

Right. Never underestimate conduction through the relatively large area of the case as a heat escape route.

I have a Cyntech case on mine and it doesn't get that hot, even when running XBMC (Raspbmc).

I bought this case, but on eBay rather than Amazon, and it came with three little heat sinks. It is on 24/7 and so far no heating problems.

OK, thanks. I'll buy the Cyntech case mentioned in the previous thread, then. Depending on how closing the case affects the CPU temperature, or not, I might drill some holes.

Thanks, that's useful. A bit of Googling shows how to graph it:

Alternative to Cyntech is Modmypi:

Dave,

You can see the CPU temperatures on my six (mostly idle) Raspberry Pi cards here:

They are in different locations, and with different amounts of cooling.

Monitoring is described here:

It's not perfect, in that sometimes I get an incorrect temperature peak recorded. For amusement, let's put them all on one graph:

Half price if you go for random (ie. left-over) colours:

Yeah that's nice too. But specifically I find the accessiblity, and so the ventilation ;-), best functional if comparing all available pi-boxing.