The SI based card was detected by windows even before it activated a driver for it (ie the first time it was ever plugged in). The JM card OTOH has never been auto-detected - allways have to scan for hardare changes in device manager. Doesnt matter whether there is an active eSATA drive on it or not.
In OSX however, both cards are detected as soon as they are plugged in, just the JM seems to not like the specific drive I needed it to work with. It has allways worked fine in EFI as well for me. Im not sure which specific JM chipset it is - the card I have is the single port OWC slim. The Sonnet tempo is also a single port.
OK - this randomness got me curious and I just stuffed them both into an old HP laptop running Windows 7/32 home premium:
The OWC JM was detected and driver auto installed correctly (Standard AHCI SATA controller).
The Sonnet tempo SI was detected as a devce, but failed to find driver. In device manager after doing a scan for new devices windows went hunting on windows update and fond and auto-instaled the correct driver (SIL storage controller) from there.
Both cards now auto detect in device manager when inserted.
To confirm on 2011 Macbook with Windows 7/64 Ultimate:
The OWC JM Card does NOT auto detect.
The Sonnet tempo SI card does auto detect and even EFS drives are accessable through it due to bootcamp filesystem driver (whereas they are not via my WD passport FW800 for eg).
On a Lenovo laptop running Windows 7/64 enterprise edition:
The OWC JM Card does NOT auto detect.
The Sonnet tempo SI card does auto detect.
So this actually looks to me like a Windows 7/64 plug and play compatibility issue and not an MBP specific issue.
(Again, ignoring that the JM card seems to hate my new 750GB WD scorpio black)
@mods - I know - were a bit OT now, but we got here (eSATA cards) exploring reasons for audio glitches in audio apps on a machine with RME hardware attached that shouldnt glitch