I built some E3 X10 systems recently with boards that have onboard LSI SAS due to them being a lower price. I don't recall the exact wattage but IIRC it was around 5-6 watts saved when I moved the jumper to disable the onboard SAS. I don't know that everything is totally disabled but there is some savings. Idle draw on those systems with the onboard SAS disabled is around 24w with a Pentium T, 2 sticks of DDR3, 2 SATA SSD's and IPMI.