@Jeff: The hardware is the M51AC, with i7 4770s, 24 GB DDR3 12800 RAM (2x4GB+2x8GB), Samsung EVO SSD SATA 500GB, onboard grafic (fancy GTX 650 removed for energy saving -> I hope greta will be thankful)
@Ramala: Found a suitible switch in BIOS: Aggressive LPM (Link Power Management). It was...