I had this issue with another Gigabyte motherboard. Infinite reboot loops at power on. All of the other parts were fine when I tested it. After testing everything I had to return the motherboard, replaced with another, different brand. Asus. Same chipset. Different brand, no reboot loops with...
800 DPI. It's slow and slower lol because I find it easier for me to control. I can adjust up and down with button press. Dun use it much. Mostly on 800.
Is nice to feel supported when in hardship. I think you may find some support elsewhere, not on Creative forums if they abuse with neglect. Is possibly better elsewhere about the card where people care. I recommend an Asus Xonar card to you or perhaps other forums where you can express and share...