the power numbers don't make a lot of sense. I suspect either the pcie interface is being kept in a high-power mode (plls running, etc) or else your molex is supplying power to other stuff on the board. (there must be a dc-dc regulator on the auxiliary card, since molex provides only 12,5.)
This is almost certainly true. I mean, we know it uses DC to DC to step the 5v down to 3.3v. But oddly, SanDisk rates the max write power consumption at 5.5w, and I could only get it max at 3.5w. Of course, it also possesses a deep slumber state, but that's contingent on having a L1.0 PCIe endpoint, and that hasn't even been ratified yet by PCI-SIG.
So definitely take the power consumption results with a grain of salt. There are challenges to testing this drive in this way.