@hfg
What was the other eSATA card you had in the machine?
And did it matter which slot it was in?
Thanks.
mdr
It was a dual eSATA 6G PCIe 2.0 from OWC
http://eshop.macsales.com/item/NewerTech/MXPCIE6GS2/
I have a 2008 Mac Pro so only have one PCIe-2.0 slot in addition to the video card slot. So the eSATA was in one of the slower slots and I think I tried it in 2 different slots with no effect. Removing it allowed booting without problems, and I used the 2nd SATA port on the Solo x2 card to cable out as eSATA to run my RAID-5 backup drive in place of the removed card.
The Velocity Solo x2 card had exceptional performance with a Samsung 840 Pro 256GB SSD mounted to it as my boot drive.
-howard