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So I recently got the new 15 inch MBP and installed Arch on it. During the installation I happened to be watching the journal logs and noticed that I tripped the thermal throttling on the CPU.
So, I ran a few tests. It seems that I am able to trip the thermal throttling on the CPU whenever I run 2 or more of the cores (8 logical cores) at 100%.
For instance, my simple test was to do this
dd if=/dev/urandom of=/dev/null bs=4M &
dd if=/dev/urandom of=/dev/null bs=4M &
dd if=/dev/urandom of=/dev/null bs=4M &Then watch the journal, sensors, and mcelog, for warnings.
Doing this I am able to trip the heat sensor ALL the time.
I installed macfanctld-git from aur and set the temps pretty low and that seems to have helped a lot, as before the fans wouldn't speed up fast enough to account for the sudden increase in CPU usage. Nevertheless if I run 2-8 cores at 100% for more than a few minutes I still trip the heat sensor, even with the fans at 100% (i.e. 6200 RPMs).
My question is, is this normal behavior, or is this mac a lemon?
The computer feels just as hot doing heavy CPU work on OS X, such as compiling llvm, but I can't figure out how to get OS X to tell me if it is tripping the heat sensor.
My hunch is that this is normal, and that Apple puts in very powerful CPUs knowing that they will have to thermal throttle them. So they use the extra power to keep the system fast even though it is down clocked.
I should also note, that even when throttled it appears to be very fast. Some anecdotal benchmarks show about 20%-30% drop in performance when it warns me it is throttling.
Thanks in advance!
Last edited by isomarcte (2015-06-13 22:17:34)
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