There are a number of posts on this matter. I took some measurements using a “temperature gun” like this one:
I found that temperatures on the top surface of the QC ran 15-20°F above ambient, where the ambient temperature was measured on a nearby expression pedal (unpowered and not generating any heat of its own).
I wouldn’t be surprised if temperature varies with CPU load. I took the above measurements using a patch running for a couple hours with the CPU at 42%. I have not profiled any devices with the QC, but suspect that the increased load on the DSPs might increase the measured rise above ambient temperature.
Subjectively, the temperature of the QC feels to me about the same as a high-end laptop that has been working hard.
I’ve had laptops go into thermal shutdown; in those cases the case was uncomfortably hot to the touch, as in my not wanting to maintain contact for more than a few seconds.