I have a HP envy 17 1ae1xx. It has a i7-8550U CPU inside. In Linux I use Intel Graphics even if the power cord is plugged in. It has a MX150 that I can turn on when I need it. I have both Linux and Windows installed. While working with octave, it randomly checked the CPU temp and realized that even at load on one Thread, it sits at 2.2Ghz. So I installed stress and created a synthetic load on all Cores for 30 seconds. The Core speed rose a little but never much more than 3 Ghz. I assumed it was a Linux problem, so Installed Heavy Load on Windows and checked the CPU Speed in Task Manager, where it just stayed between 2.3 and 2.2 Ghz, even though it was at 100% load on all Cores. I also tried the same with HwInfo. The Fans started spinning up after a few minutes, even though the CPU was still sitting at 2.25 Ghz, which is close to its lowest speed at 1.8Ghz. Does this mean my Computer is thermal throttled? Or what else could I do to increase perfomance or test for problems?
2 Answers
Loading up all cores will hit the thermal limit faster and so it will boost closer to the base clock of 1.8GHz.
If you want to see a higher boost clock then you want to have your system lightly loaded and use a single core stress test. Even then your laptop may have another thermal limit preventing it from boosting much above the base frequency.
Designers can put power and temperature limits on devices, so it may be that your system is power throttled while never really hitting a thermal limit.
The only figure you can expect to hit is the Base Frequency of 1.8GHz. Bosting above that is dependant on power, temperature and other factors that only the laptop designer can truly know about.
You should consider 1.8GHz the "normal" guaranteed speed, not the "lowest" as it should be able to clock a lot lower than that to save power. My i5-6300U laptop regularly goes as low as 600MHz and up to as high as 2.8GHz even though its "base" is 2.4GHz.
You could well still be thermally throttled, but your manufacturer could have put some more limits in place..
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Boost usually pertains to one core, and entails directing more power to that one core, while reducing power to the other cores.
Once you have stressed all 4 cores of the i7-8550U, you then actually prevent the boost.
Note also that even on the one core, the CPU firmware decides on the boost with the idea of preventing over-heating, meaning that the boost will oscillate up and down with peaks that might last only a few milliseconds.
The performance numbers that you see are only an average, so the boost could well have happened, but the average you see is lower. Do not expect that number to ever hit maximal boost and stay there for an appreciable amount of time.
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