I have been looking for the above card to provide a 20-pin header for an older motherboard that has no USB3.0. They all seem to require external power in the form of either a SATA or Molex power connector. After a bit of searching I found this adapter. I was hesitant to get it in case the PCIe slot maybe couldn't handle the 4.5W required for up to 6 units of load. But the PCIe X1 slot should offer at least 25W as per my research. Would this adapter work OK with only 2 x USB front panel headers load?