I've got a Mac Pro with the Apple RAID card (Slot4), I've put a Sil3132 PCI-E eSATA card into Slot 3. I can load drivers (v1.1.9 Silicon Image), and see the eSATA card in the System Profiler.
Hi,
I have seen system conflicts occur when both the Apple RAID card and SI drivers were installed. It may also be another driver that is causing the issue. To troubleshoot this issue I would install a fresh copy of Mac OS X on a spare HD using the Apple DVD and boot from it. Next, install the SiI-3132 1.1.9 driver, reboot and see if the issue still exists.
If the issue is resolved you will know something else is causing the problem on the regular boot disk.
Another possibility is that the SiI-3132 card has the RAID BIOS flashed to the card. This will usually occur if the card is purchased from a PC vendor. In that case, the card may not work unless the Mac SiI 3132 32-bit universal SATARAID5 driver is installed OR the card is flashed back to BASE BIOS.
You can find the drivers here:
http://www.siliconimage.com/support/searchresults.aspx?pid=32&cat=3
Unfortunately, there is no Mac driver uninstaller provided by Silicon image and the different driver versions install several files in different locations. This is why it pays to buy the SI controller from a Mac based reseller that knows what BIOS is installed. If you did not purchase from a good Mac reseller then it is best to test the card with a spare boot disk that you can erase if the wrong driver is installed. I would not want to mess up my main boot disk with these driver tests 🙂
Have fun!