Tobias, definitely an ATX motherboard will consume more power than a Micro ATX since it has more chipsets and memory DIMMs included on it.
The difference between the two devices is not significant; it will depend on the additional components that are being installed on the board itself, like the processor, memory, video card, hard drives or SSDs.
The following information can be found on the TPS of both motherboards (page 56 or 57)
- For example, for a high power system consisting of a supported 95 W processor (see Section 1.3 on page 16 for a list of supported processors), 4 GB DDR3 RAM, one high end video card, one hard disk drive, one optical drive, and all board peripherals enabled, the minimum recommended power supply is 460 W.
- For example, for a low power system consisting of a supported 45 W processor (see Section 1.3 on page 16 for a list of supported processors), 2 GB DDR3 RAM, integrated graphics, one SSD, one optical drive, and no extra onboard peripherals enabled, the minimum recommended power supply is a 320 W.