I've been working on Esata hd's all week on a P35 ds4.
I wanted to be able to switch 5 hd's off through the night on my Server, and managed to get it working yesterday.
I didn't change the bios options, and left the setup as sata drives.
I also added two pci-e sil 3132 sata cards, one raid with Esata connectors.
I can now see 3 hard drives in the usb add and remove gadget, but still have two missing. It see's one on the 3132 which is in a external caddy, and two on the purple sata's on the m/b (Jm). Even though all are listed in device manager, the only way to remove them, is using that app "hotswap".
This app will turn selected hd's off, but will rescan for them when needed.
For some reason, if I put one of the two hd's into a external caddy, and plug into the external e-sata port on the 3132 it's then seen in the usb list.
I do hope this helps others, but using that app means I can now turn off 5 hd's overnight, remove one from the esata port, replace, and re-scan for them in the morning.