New hard drive, internet slow.

Hello guys, few months ago i got a new PC but soon realized that my Hard drive had some problems that causes the computer to restart. So i got a new hard drive and installed it on my computer.
I used a windows 7 disk to install the OS and used the CD that came with the mother board to install my drivers. When i turned on my computer after installing the new hard drive, everything seems fine, however, i realized that the internet became extremely unstable.

When i open up internet browsers, sometimes it loads instantly, but sometime it takes forever. (usually refreshing it many times will make it work) However, when i try to download anything, the download would start off with decent speed, (1-5 Mbps) and drop down to <10Kpbs within seconds. Eventually the entire download stops and never resumes.

since my PC does not have wireless i could also connect with my ethernet.

Also, when i switch back to my old hard drive, the internet speed becomes good again.

So far i've tried :

- Chrome and IE, same problem exists for both browsers.

- ipconfig /flushdns , ipconfig /release , ipconfig /renew

- netsh interface tcp set global autotuninglevel=disabled

- reinstall OS and Drivers

- Speed test. (dl speed around 9.0 Mbps and upload 6.0 Mbps)

-boost in safe mode

heres my computer:

- Operating System: Windows 7 Home (64-bit Edition)
- CPU: Intel® Core™ i7-5820K Six-Core 3.30GHz 15MB Intel Smart Cache LGA2011-V3
- Motherboard: ASRock X99 Killer ATX w/1 x Intel LAN, 1 x Killer LAN, 3x Gen3 PCIe x16, 2 PCIe x1,1x Ultra M.2, 10x SATA 6Gb/s
- RAM / System Memory: 32GB (4GBx8) DDR4/2800MHz Quad Channel Memory (ADATA XPG Z1)
- Video Card: NVIDIA GeForce GTX 980 Ti 6GB GDDR5 PCIe 3.0 x16 Video Card (Maxwell)
- Power Supply: 800 Watts - Standard 80 Plus Certified Power Supply - SLI/CrossFireX Ready
- Hard Drive: 256GB SANDISK + 3TB SATA III Hard Drive Combo (Combo Drive)

(original hard drive replaced with : WD Blue 1TB Desktop Hard Disk Drive - 7200 RPM SATA 6 Gb/s 64MB Cache 3.5 Inch - WD10EZEX)

i tried to find solutions online but it doesnt seem to fix my problem. (note that my internet works fine when i switched back to my old hard drive before it completely died)

*also, i live in a dorm and all i have access to is the ethernet plug on my wall.

Golden said:

Is Windows 7 updated fully?

When i try to check windows updates, it stays at the "checking for updates" page forever
i assume it is because the slow internet causing me not able to download / check all the updates.

Golden said:

There are quite a few too update, so I'd say thats why its being so slow. Leave it to update - it may take several hours.

ok i've left it on for ~30 minutes now it is still checking for updates (nothing has been downloaded)
is it taking a bit too long?

is it possible to download the update files on another computer and transfer it via usb etc?

Golden said:

No, thats normal for a fresh install. Leave it for several hours.

No, its not possible to do via any other method.

ok, so i installed all the updates, it is still the same.
when i open networking in the task manager while download thing
i see the graph spike up and down in a pretty regular pattern. im not sure indicates anything though.
what should i do next?

ok i think i fixed it.
i checked for updates a couple more time and made sure all the ones that failed to install installed properly
thank you so muhc for the help!