Have decided that that I need to investigate this ....so

Bought a few ext usb/Esata cases and some sataII drives plus some Akasa Sata backplates.

Test machines are various MSI K9mmv and GM? AMD2 mobos running Sata HDDs.
Put the backplates in & connected to SATA on mobo.
Rigged up the Ext Conn with the SATA in the cases
Set the boxes to Esata - Hot plug them - not detected.
Cold plug gives a BSOD.
Ext HDDS are WD Caviars.
They work on USB2
Latest VIA Onboard - clean machines.
Wonder whether it could be chipset on ext drive enclosures?

Any ideas folks?