I spent a few hours attempting to get this to work and the problem that was preventing me was that I was installing SweetLow's certificate as Current User and not Local Machine. Anyway I will post what I did to maybe help some of you people having issues with troubleshooting.
I'm on Windows 10 Pro 10.0.18363 Build 18363 and my motherboard is from Gigabyte.
I used vadash's 1000hz from github which includes everything you need here: https://github.com/vadash/1000hz
-Disabled xHCI in BIOS
-Set bcdedit -set loadoptions DISABLE_INTEGRITY_CHECKS
-Set bcdedit -set TESTSIGNING ON
-Installed SweetLow Certificate (Make sure you install it under "Local Machine")
-Copied atsiv to C:\Program Files\atsiv
-Found Mouse ID with atsiv
cd "C:\Program Files\atsiv"
.\devcon.exe find *mouse*
-Created atsiv tasks in Task Scheduler copying MouseOC_1.xml & MouseOC_2.xml profiles from 1000hz-master
Note: Change the Mouse ID to match yours in the arguments, also the XML files would not import so I had to create new tasks & manually copy the arguments/actions/settings. You can still view the settings/properties from the MouseOC XML files but not import.
-Run Setup.exe, Filter On Device @ 1000
-Install Service, click Restart.
You should now have 1000hz.
This is what worked for me, I hope this might help some people who are lost in this thread.