Help Please

I have been having problems with my computer for around the last 2 weeks now. the issue is that out of no where it just started to get slow i have never had these problems before i have done a complete windows 7 reinstall but that still didn't work. I also ran the fur benchmark thinking that it may be it and read that if u see black squares or something like that it means that ur graphic card is broken but i saw none of those but i didn't have it on for long because my graphic card was getting over 60 and it started to worry me im not really experienced with that kind of stuff . i also ran all kinds of tests thinking that it could be my HDD i ram the chkdsk command, disk cleanup, error checking, and even software but they sat that everything is fine with them. i do not believe that its a virus or anything either because i have done all kinds of scans with avast and malwarebytes (Both Pro) and they have found nothing. i tried cupid hw monitor but all my temperatures seem fine and normal my fans arent clotted with dust especially now i just finished cleaning all the fans and at this point im at my witts end on what it could be and i need your help.

System Specs:
i7 4770K 3.50ghz ( oc genie) 3.9ghz
Nvidia GTX 980 Classified
Gskill 16Gb Ripjaws ram DDR-3
Msi z87-g45
Corsair RM 850
old ps4 factory HDD from Samsung 500 GB ( OS installed on here )
WD 1tb ( all games and such )

^^^ this, do yourself a favour and have your OS re-installed on a ssd or new(er) hdd. Those old ps4 hdd's are slugs of things, terrible quality at best.
Temps are very good as well for your GPU.

ya i was looking at that i just finished doing a windows index rating and everything was around 7.8 but the data transfer rate was a 5.4 so i was starting to get suspicious. thank you so much though deejeta i really needed help i already ordered 2 segate 2 Tb SShd from amazon (are those good the reviews are really good but idk if there real hehe) i also posted this same post on tomshardware but that was like at 10 a.m i just out this up on here like 10 min ago :)

Based off your description and specs I'd also have to say that it's attributed to your hard drive, you're using a 5400 RPM HDD as your boot drive as well as it's possible that it's starting to fail if it's been getting even slower

Please run CrystalDiskMark so we can see the read and write speeds, and then CrystalDiskInfo so we can see your drives health status, SMART data, and temperature

CDM Disk C -
CDM Disk Z -
Crystal Disk Info -

here you go 100557662 also thank you :)