External Hard Drive ACPI Support (timeout)

Just out of thought, who has an external HDD and functioning on ACPI support to timeot if set to fixed timeout in power settings?

I can use IEEE1394 firewire external on each !945GM (mobile) !955, X38 and it functions fine. But for USB on these mobos, HDD timeout does not comply. I also just tested my eSATA HDD box to SATA on rear panel of the X38 based ASUS MAXIMUS FORMULA SE (this mobo has no actual eSATA so I had to use I/O plate and a SATA to eSATA cable) and it will not enter timeout even after many minutes beyond as set in power scheme. all internal HDD units and firewire HDD times out in 15min inactivity. the same firewire box used as USB will also not timeout.

Now, oddly enough, the same firewire box that complies with HDD. I will also test the dedicated eSATA on !955X ASUS P5WDG2-WS to confirm if it works like that. timeout on the !955 and X38 does not comply on an older !875. I have a P35 but forgot to test.

I this a chipset issue or dirver or individual HDD or network configuration that can be adjusted? Is there a suspend or timeout setting for USB ports?

Hope to get some kind of feedback if at the very least to know it's not just my stuff.

Thankx in advance!