With my previous keyboard (Logitech 710+), I never had the following issue.
After installing a new K95, my PC will stay stuck on the BIOS loading screen indefinitely when restarting/fresh boot. The remedy is actually unplugging my Razer Deathadder mouse from its USB port. Once that is removed, it boots fine. I can then plug the mouse back in, and it all works perfectly fine (both kb and m).
This only started happening after plugging in my K95 keyboard. The very first time I plugged the keyboard in, while PC was shut down, it didn't boot. I hit the reset button on my PC and it actually booted. But now, it just simply never boots, even via reset button, until I unplug the Razer mouse.
Has anyone ever heard of a K95 causing this problem in combination with a Deathadder?
Edit: It might be important to note that the keyboard is unresponsive during the BIOS splash screen. Hitting the button to enter BIOS, or any of the others, do not do anything.
This is the case both when it won't boot b/c mouse is plugged in, AND when it does boot with the mouse unplugged.