Strange video playback issues, no clue why

Hello guys, this is my first post here.


I'm experiencing occasional stutter when watching 4K (even 720p/1080p @ 60 FPS) videos both on YouTube and files downloaded on my SSD, with MPC-HC. On YouTube (Chrome), I've been dropping frames on heavier videos. The likes of 4K/60P, but the ones that are 4K/24/30P seem to be perfect with 0 drops. The 60FPS (even 720p/1080p) ones are a different story.


My CPU is Intel Core i7 6700K, and as far as I know, it supports smooth playback at 4K and 60 frames per second. My internet connection is also pretty good ~60-80mbps. I also want to note that I'm using the integrated graphics card on the CPU, as I do not have a dedicated one currently.


I opened Task Manager 5 minutes ago, and I noticed that every time there's frame drops, my CPU usage spikes up. Please, take a look at this screenshot:


http://postimg.org/image/r9pnl6f4v/full/


Why does this happen? Isn't the CPU powerful enough to play 4K/60P buttery smooth? Why the spikes?


A few quick notes - all system drivers updated, latest bios, no overclocks, everything's stock, no other tabs in Chrome, no other apps running, @ High Performance, CPU temps are perfect ( low 20s, even 18-19c when Idle - when watching those videos - no more than 50-60c). Tried other browsers - no change. Tried flash - worse.


I just noticed that even on videos that are 720/1080 @ 60FPS it stills drops a lot of frames, even though CPU usage is like 10-15%... I even tried switching the codec - from VP9 to MP4/VC1 (through an YouTube extension), and it still drops frames. So it mustn't be the codec either. It doesn't matter if it's full screen or not. I guess there's ALSO a problem with the videos being 60 frames per second. I just ran a 4K@30P video for 40 minutes on repeat and there wasn't a single frame drop, so yeah.. what the hell.


https://youtu.be/bhFTsEYyFiA - A video example that drops frames in YouTube. It also stutters on the computer with MPC-HC.


Can anyone clarify if the 6700K is/isn't powerful enough to play 4K60P perfectly (on its own)? Maybe I need a dedicated graphics card too, in order to play those video smoothly? Because if the iGPU is helping, which I assume it is, since Hardware Acceleration is enabled (and when I disabled it, clips got completely unwatchable).. this should mean that it's not strong enough to help out the CPU. Which leads to the conclusion (if that's true) that you definitely need a dedicated graphics card for stutter-free playback and no dropped frames, especially at 60P. Correct me if I'm wrong.


I hope that I've been clear enough with my issue and I want to thank in advance anyone who might chime in!