I believe the card still needs assistance from the motherboard chipset. You should contact Marvell and find out if they have tested their card on this PC model.

Pablitus my friend, it appears we maybe in a similar boat you and I! en.community.dell.com/.../19965137.aspx

From your post it seems like the Optiplex 790 doesn't like Marvell Chipsets either (or Silicon Image based ones in my case) can you post the exact model number of the card you've purchased? In addition have you tried your luck with the absolute latest BIOS A07? Its still not working for me either, but I thought I'd give you a heads up. It seems like our last choice is to attempt a JMicron based board, but I'm having a hard time finding a source for one.

Hi,

Adding my experience to this thread:

Purchased today an Adaptec 6405 RAID controller. My OptiPlex 790 with A10 BIOS did not want to boot with the RAID card in it. Upgraded to A11 (latest as of today) and it started booting. During the installation of Win7 I've loaded the driver from the Adaptec CD and the RAID volume was not even recognized by Win7. Tried latest driver from Adaptec site, same. Suspecting that something is not ok with Win7 or the Win7 driver, tried to boot from the Adaptec CD that has a bootable ISOLinux on it with the driver for the card. It got frozen, did not boot the Linux. Without the card the same CD boots just fine. I suspect the PCM Sierra chipset is not agreeing with the 790 motherboard's one. I'm stuck.