Intel Core i5 at 4K video at 100% load - Pentium 5405U at 50% at 4K - why?

Co
3

My Core i5-7400, a relatively decent part that will be replaced soon anyway, has problems playing 4K and 8K videos on YouTube, via Chrome, Edge etc., everything has already been tested. Actually, my Core i5 should do that easily, right? Even my notebook, whose performance is equivalent to a Core i3-7100, manages this without any further problems. I have read in some forums that the hardware acceleration is a problem, but I have already deactivated and activated it, both without any "significant" improvement. But since I don't add half a thing here, here are some key data, so, I have 16GB RAM, an RX580 and the i5. Even a friend's Core i5-9300K (notebook CPU) does better… But why does my i5 have such problems, and what is the cause? I did a GPU upgrade in December, from a GTX 750ti to the RX 580, and before that he had no problems at all.

I ask for quick help!

pu

The processor is not entirely responsible for video playback. Your graphics card is completely responsible for this. As soon as a graphics card is installed, it is used for video playback. Your i5 works so hard that your graphics card can't, and your processor has to help. Did you install all drivers after changing the graphics card? If not, you should definitely do it.

Co

Well, this somehow speaks against it

Co

https://photos.app.goo.gl/5nVEfpFG4hR3HXtF6