Yeah, the motherboard doesn't really care what GPU is installed, so long as it's a UEFI motherboard from the last decade or so. As far as the motherboard is concerned, it's giving off the 75W of PCIE slot power to the GPU and the rest is "someone else's problem" AKA the PSU. Whether or not an RTX 3070 has enough power (both in wattage and quality) comes down to the exact PSU.