No, it's just the button specific for the "Bios Flashback" system of Asus.
You can see it on this picture, near the red esata.
http://www.asus.com/media/global/products/gD1HelDX8lh3WSpG/5z5mSBqJuB5f9I10_500.jpg
Well, my problem is solved.
My first try was to modify some properties from the bios as you suggest Draconian. Unfortunately for me, nothing works. More things I change... worse it was. At the end, I got the red cpu led at the first boot which I never had before (only on restart).
From...
Our problem with the red CPU_LED is not common I think, because people have generally this problem at the first boot, sometime randomly but when they got it a simple reboot can't fix it.
For us, everything is fine except after a reboot and a simple start/stop fix it. As you, my fans are not...
Hey,
I've exactly the same problem as Draconian but I've a completely different configuration, except the i7-4790k.
Asus Sabertooth Z87
Intel i7-4790K
G.Skill ram
Be quiet power supply
And I tried the same things to solve the issue and nothing works but I didn't try to increase the voltage...