First of all - thank you for keep writing suggestions!
Oli:
Your right regarding the mainboard. I came to the same conclusion. And HP and ASUS writes that you should use the HP BIOS software. And I have the latest version.
I do not have the guts to do different.
I'll have a look at the chassic fan.
sumo:
I'll have an extra look at the BIOS.
Btw it's an old style BIOS. No drop-down.
I'll be back.