PCIe eSata attached HDD changes boot order, but only when plugged in

My system was running smoothly until I added a PCIe x1 eSata card ("ASRock sata3 card" with Marvell 88SE9123 / 88SE9120 chipset) that uses a Marvell Magni controller with a driver version 1.2.0.1014 . The Marvell card driver installed OK; the board is recognized at boot time and recognizes the HDD when it is attached (a Freecom Hard Drive Quattro, 2 TB with USB, Firewire and eSata interfaces; it houses a Samsung HD204UI disk).

When the HDD is not plugged in the systems boots OK, but when the HDD is plugged into the Sata 3 card, the system fails to boot with the message: "Reboot and select proper Boot device or Insert Boot Media in selected Boot device and press a key".

When I interrupt the boot process during POST to force the system to boot from its "Intell0" RAID0 HDDs (which otherwise works fine) the system ignores the setting and keeps trying to boot from the eSata attached Freecom drive.

I have updated the ASUS P8P67 rev 3.1 MoBo bios to 3207; the Marvell drivers for the MoBo to Version 1.0.0.1045. I have disabled and enabled the Marvell controller OPROM in the bios - no difference. The Freecom HD is OK - works fine on another machine. The onboard ASUS eSata connection (also with Marvell) works with the same Freecom disk - no boot issues, regardless whether the HDD is plugged in or not. I have also checked that the Freecom partition (there is only one) is inactive.

The ASRock Marvell controller is the first to load when booting, then follows the MoBo ASUS Marvell controller. Both are displayed at boot time, before the other drives are activated. It seems that the ASRock Marvell controller hijacks the boot order and sets it to point at the HDD attached to it. When no HDD is attached the problem disappears. The ASRock OPROM might dictate the system to boot from its attached HDD, but I am not sure this is what is truly happening, or how I could change this.

I found a workaround after updating the Marvell 'Magni' drivers for the Sata 3 card as posted on the ASRock website. This changed the driver version for the ASRock PCIe card to version 1.0.0.1028, and the driver version for the ASUS onboard eSata Marvell drivers to version 1.0.0.0022. When booting with the Sata 3 card HDD unplugged, the systems boots fine (as it did before), and when the HDD is plugged in after Win7 has started, it connects without a problem. Booting with the HDD plugged in however still does not work. This workaround might also work with the previous driver set; I have not tried this out yet. I am semi happy with this result; it is sufficient for back-up purposes.

A hint could be that updating the Marvell drivers downloaded from ASUS vs ASRock produces different and distinct driver versions for all Marvell devices. It seems that they cannot be updated separately (the driver installer is an exe file, no inf is available).

Another idea stems from a similar experience with an older eSata PCIe card: PEXESATA2 from StarTech which is based on a Silicon Image Sil 3132 SATALink controller with driver version 1.0.22.3. This controller has a separate flash bios capability which might allow for more specific tuning. I have not researched this in full because after equally failing to boot I hoped to solve the problem by buying the more recent eSata ASRock card. The fact that both produced the same error with two distinct controller architectures suggests that the ASUS bios might be the culprit.

A final possibility is that the Freecom HD influences the boot order (which it could only do when plugged in), but this seems far fetched. Moreover, its single partition is set to 'inactive', ie not bootable.

Any ideas?