Random Audio and Video Stuttering

[TJCAT]

Hey, so recently I have had a lot of issues with my PC where sometimes i would randomly get stuttering (audio and video) where i could be playing games, i could be watching a YouTube video it doesn't matter, i could be doing anything and randomly audio will stutter (pause and play as if it hadn't been loaded) and video in games will drop from 70fps to 21fps recorded but morelike 1 fps, i've analysed my PC in task manager and recorded what tends to happen most regularly when this happens, i've been recording this for about a week or two now and it tends to occur when my 2 year old Seagate 1TB HDD has to read or write a largish abount of data (random Antivirus scans or Windows scans) although i do not understand why this would slow down audio and video when im doing stuff that is stored on my SSD (OS is also on SSD)

Yes I have tried defragging the drive in Windows, about 4 times

My PC specs:
i7 4790k@3.8Ghz with a Antec 1250 AIO
Gigabyte H81M Rev 1.0
GTX 750Ti FTW (plan to upgrade to pascal, even then this thing still rocks strong)
128GB Samsung 850 Evo
8GB RAM @ 1600Mhz (I have checked, i never run out of RAM)
Seagate 1TB HDD (2 years old now, these things are tendant for short life times, if i knew that whilst buying it i wouldnt have purchased it, even then a dying HDD should straight up BSOD if its dying right?)

Another reason for my suspicion of it being the HDD is this:
https://gyazo.com/08cf6f60321fdbe93d86af8d492a0802
0.29MB/s 4k read and write, a bit suspicious......
SSD on the left, HDD on the right.

 

[TJCAT]

ended up trying a boot scan on all drives, then a full scan in windows and de-fragged the drive, seemed to stop... ups...