CPU Clock speed drop

[Gab0x]

So here is the thing, my CPU (laptop) runs on a base clock speed of 2.9 GHz, but even when idling on 10% usage it runs on 3.4 GHz. When is hit with a heavier load, for example gaming, or even just after booting windows runs its shenanigans it drops down to a 0.4 GHz. I ran a stress test to figure out what is it. According to HWMonitor on 100% usage, 3495 MHz, it drew 24.98 W-s before dropping to 399 MHz 2.8 W. After that the power consumption was capped at 15 W and the clock speed on 2.45 GHz and was about 84% usage. I don't think it was thermal throttling, the temperature never went above 84°C. What causes this? What can I do? I don't mind loosing some speed for stability, I use this machine as my daily driver not for heavy gaming.

[G00fySmiley]

run HW monitor and see what it has for max.what cpu is in the laptop? and what kind, the laptop manufacturer or the chip maker might have set the thermal throttle point at 84C. 

[Gab0x]

Tjmax is 100°C and TDP limit is 15 watts. Its a Intel Core i7 7500U. 

[Gab0x]

Am I wrong to assume that in case of thermal throttling, the system would only dial back the performance for stomp on the brakes? This doesn't seem normal to me.