Ok I got a asus crosshair v formula z, and every time I power off the system my next boot give me a Cpu fan error and makes me go into the bios. I have 2 noctua nf-f12 pwm fans on a y splitter it came with on Cpu fan header.
So while watching my heatsink on boot up I figured out why it was giving that error, cause it still did it after I took out the splitter. One of the fans on my heatsink doesn't spin right away, it waits 1-2 seconds the spins. But anyways I updated the bios and now it doesn't error on me.