See this post: https://forums.evga.com/FindPost/2731572
If the button is lit it means the LED Sync will start-up with Windows, so you have to make sure it is no longer lit.
A task will be created in the Windows Task Scheduler for this seperate tool.
 
If you can't fix it you may want to try to remove that schedule entry manually (LEDsync.exe) or uninstall Precision XOC completely and install it again.

Mase123y
Thanks a lot

Hopefully that fixed it. 

Unrealitysireal
I'm actually having an issue with the "fix" for this. I recently replaced the heatsync of my FTW3 with a waterblock, so it's no longer connected to the RGB LED. Since there's no LED, the LED button is greyed out, so I can't click it to prevent LED Sync from running on startup. Is there any other work around?

Do the following:
 

1. Go to start or Press Windows+R.
2. Type in: taskschd.msc and run it.
3. Remove the LED Sync entry.

After this it should be removed from the taskscheduler the manual way.

I have had this issue and I agree it is very annoying to deal with this constantly asking for UAC permissions at startup. What I did that fixed my issue:

1. Type in schedule in the search bar. Schedule tasks will pop up. 
 
2. You will be able to find "LED Sync" in the processes. Click on this and properties appear.
 
3. Click the box that says "Run with highest privileges"
 
4. Also, make sure that the "Configure for:" box is selected to your version of windows. 
 
See the screen shot for an example. 
 
I hope this helped.