idle system 150W
This is with all of your risers and cards plugged in right?
Gpus drain some power by just being plugged in. If you want an accurate measurement per card then unplug all of your GPUs and risers and then measure your idle consumption. If you have an ssd and a later generation cpu it should be around 30-40w
Yes, it's okay. This is with all 8 cards connected. "Idle" means everything ready for miner start. :-)