mew

I can't get it even to Clover (the USB sticks run fine on other PCs, but on this one it simply skips the drive..... Tried booting from a bootmanager on USB stick (PLOP) however I get an error that the drive doesn't contain a valid boot sector signature ( i've tried 10.9 image, 10.9.5 and 10.10)

Any idea why the USB Pen won't boot on a HP DC7900? I've read some good feedback over at tonycrap....