Actually, to test a PSU at 80% load isn't exactly fair, since no PSU, regardless of brand or type, should ever be used above 75% capacity. 50% is usually the sweet spot for efficiency on any PSU, not just this one. Also, it would have no problem powering 2 mid-range GPUs. For 2 GPUs, 150W of the total comes from the PCIe slot (75W per slot) itself, which is a large chunk of the burden this drive bay PSU doesn't have to deal with. It'd do just fine.