Internet is Slow on One Computer

[cabooseplays]

Recently (within 2 weeks), I have been getting an extremely slow internet connection on my one Windows 10 PC. I used to get about 10-11 Mb/s but now I'm only getting about 18 Kb/s. I have reinstalled Windows 10 to no avail. I have also recently installed a Gtx 1080 into my system from my old Gtx 1060 3Gb and a new 1Tb Hard Drive. I use a wireless connection from my router which is not very far and I have not move my PC recently. My computer specs are listed here:
CPU: Intel Core i7-6700K
GPU: Nvidia GTX 1080
SSD: Adata Premier SP550 120GB
HDD: WD Blue 1TB
RAM: Crucial BLS8G4D240FSB.16FBD2 2x8GB
MBD: Asrock H110M-DS/Hyper

If anyone can please help me, it would be gratefully appreciated. Thank you.

 

[Paul NZ]

Did you unplug the other hdd if you installed windows on the ssd?

 

[cabooseplays]

Did you unplug the other hdd if you installed windows on the ssd?

I have removed the old hdd and installed the new one and Windows is on a separate ssd.