It seems to me that there's some confusion on your part about what a SATA power connector is... The SATA edge connector is divided in two parts, a larger one and a narrower one. The narrower one is the signal, or data, connector. The larger one is the power connector. Some older drives also had an additional common Molex connector for power, for compatibility reasons, since at first only a few power supplies had the SATA power connector. Note that the Molex connector does not enable the hot-plugging and unplugging of SATA drives. This needs the 3.3V supply that only the SATA connector provides. As far as I can see, the ST3250318AS does not have such a connector. The manual for the ST3250318AS is here: http://www.seagate.com/staticfiles/support/disc/manuals/desktop/Barracuda%207200.12/100529369b.pdf On page 28 you can read about the SATA cables and connectors. The pins you refer to, which are not present on the WD at the same position, are NOT power connections, that is a jumper block as you can read on the first image of page 28. The manual states the following: « It is usually not necessary to set any jumpers on the drive for proper operation; however, if you connect the drive and receive a “drive not detected” error, your SATAequipped motherboard or host adapter may use a chipset that does not support SATA speed autonegotiation. If you have a motherboard or host adapter that does not support autonegotiation: -Install a jumper as shown in Figure 1 below to limit the data transfer rate to 1.5 Gbits per second (and leave the drive connected to the SATA-equipped motherboard or host adapter that doesn’t support autonegotiation) or -Install a SATA host adapter that supports autonegotiation, leave the drive jumper block set to “Normal operation” (see Figure 1 below), and connect the drive to that adapter. This option has the benefit of not limiting the drive to a 1.5 Gbits/sec transfer rate. » I think this is not a power connector issue. The WD is a SATA3 drive (6gb/s). Are you sure that your motherboard supports SATA3 drives? Maybe SOME ports support them while others do not? If not, can you force the WD to operate in a lower mode? Some drives can, either by hardware or software.