Any updates to this issue? For my XPS 420 I bought a Roswill RSV-S4-X port multiplier with SiliconImage 3726 chipset and Matrix Storage Manager says only Port 0 will be active (like all of the current comments here).
Next I installed the eSATA PCI-e adapter that came with the box. Windows 7 x64 RTM found and installed drivers for the card and they work fine for all 4 ports inside the multiplier....... that is until the system sleeps. Upon resume from sleep, the device (eSATA card) is no longer present and I need to reboot to get it back.
Frustrating. But I thought I'd mention it here in case someone else has had success getting the onboard Intel eSATA to support more than one port. I've emailed Intel and will post here if they have anything to help.
When you install the Intel software, it permanently replaces the Microsoft HDD driver the the Intel one. Even if you remove the Intel HDD software app, the driver stays behind.
What you need to do is remove the included PCIe card and fresh install Windows 7-64 . Then install Intel chipset drivers (only) and all proper Dell drivers as needed. However, DO NOT install any Intel Matrix Storage or Intel Rapid Storage Tech. software.
Then, test the RSV-S4-X in Windows and after sleep. If it doesn't work (or you are just curious) re-install the included PCIe card. Try it with Windows and sleep test. You might find that one or both ways work and it was the Intel HDD software causing the compatibility problem.