Uhh, that's the BIOS splash screen, it's supposed to show that, does it get stuck on it?
Why do you have 3 keyboards and 2 mice though?
and what do you mean by "main power" do you mean the switch on the PSU on the back of the computer? don't use that to shut it down. Do you mean the power button on front of the computer? also don't use that to shut it down unless you absolutely have to. You should use the Windows Shutdown command to turn your computer off, and then you can switch off the switch in the back to disconnect it from all power sources. But that's excessive unless you're going to move the computer or open it up and change hardware.