Less motherboard really equals to less power consumption? I have four rigs with 6x GPUs in each but the frame can contain 12x GPUs each too and I have a motherboard among the four rigs that can contain 12x GPU, a friend came by and said I should just out 12 GPUs in the MOBO says I will safe more power this way
Disconnect all video cards and use a multimeter to see how many watts your motherboard is consuming from the wall.
Modern motherboards with a processor consume 50-70 watts. If you use a USB flash drive instead of a hard disk, then this is an additional 20-30 watts of savings.
A mining farm with 12 GPUs is harder to maintain, and you lose more hashrate on crashes.