Question CPU usage is locked at around 50% when using dedicated GPU but never locked when using integrated GPU

[Ridho_Strife]

Alright, so here's my spec

Acer E5 475G
Intel core i5 7200u 2.5 ghz
Intel HD 620 integrated gpu
Nvidia 940mx
8GB ddr4 ram

I was playing some game with my laptop that I didn't use for gaming for like 6 months or so (I get back playing games after I quit playing it). I noticed that when I first started the game, it was at nice and steady 60fps, but then in the next 5 seconds it dropped to 20fps, it doesn't even got heated up. Then I checked the usage with Task Manager and realized that it only uses 50% of CPU and 100% of GPU. Then I started the game again with Intel HD (I was using 940mx before) and yes, it doesn't get better, but I noticed that this time, CPU usage is more than 70% now. I've searched a bit that using integrated GPU doesn't really affect CPU usage.

Is something wrong? Do you guys have any idea what happened?

 

[rgd1101]

if the gpu at 100%, that the problem, check the temp?
lower detail/resolution?

 

[Ridho_Strife]

if the gpu at 100%, that the problem, check the temp?
lower detail/resolution?

Everything on low, 720p, and the temp is around 70-80° C

Power and battery is maxed up, I'm using high performance mode

 

[rgd1101]

what the ram usage?

 

[Ridho_Strife]

what the ram usage?

50-60%