I have published this information to assist others in Implemnting USB 3.0.
System and Equipment:
-Mac Pro, Early Edition
-2.66 GHz Quad-Core Intel Xeon
-16 Gig Ram
-Mac OS X Lion 10.7.3
-Three Open PCI SLots, 2-X4 and 1-X16
LaCie USB 3.0 PCI Express Card
LaCie Rugged Triple USB 3.0/Firewire 800 External Drive
Highpoint RocketU Quad USB 3.0 for Mac PCI Express Card
Seagate GoFlex Desk USB 3.0 External Drive
The system worked improperly with the Lacie Card.
The system is working properly with the High Point Card
I began by purchasing and installing a LaCie PCI Express Card. After discovering that the card and drivers (PXHCD.kext) do not support non Lacie Drives, I purchased a LaCie Rugged Triple USB 3.0/Firewire 800 drive.
After attaching the Lacie drive to Lacie USB 3.0 card, the drive mounted. However testing revealed that large transfers failed. The drive worked without any problem when attached via the Mac Pro's USB 2.0 or FIrewire 800 ports.
After some time working with Lacie support, I decided to order the Highpoint RocketU Quad USB 3.0 for Mac. This card features USB controllers for each port thus the card is rated to deliver up to 20 Ghz of compbined bandwidth. Per Highpoint documentation, other implementations share a single controller and thus total combined bandwidth of multiple ports will be only 5 Ghz.
After plugging the card into to an X16 PCI express slot, neither the Seagate nor the LaCie drives would mount. I could see them in system profiler under USB SuperSpeed Bus. Profiler is under Apple Menu -> About this Mac -> System Report.
After checking logs and and seeing conflicts with the PXHC.kext extension when restarting in verbose mode (command-v), I renamed the PXHCD.kext extension to PXHCD.kext.lacie in /system/Library/Extensions. Note I had to sudo -s to get root permissions to do this.
After the kext change and reboot, the Seagate drive came right up. However it mounted as R/0. When I first installed the drive, I used seagate tools supplied with the Drive Software to allocate all space on the drive as a NTFS partition. To get going with this drive, I reinitialized the drive as Mac OS Extended (Journaled) using the Erase Tab in Disk Utility.
The drive now works with out hitch.
The following benchmark results for transfer speeds were created using the "Black Magic Disk Speed Test" available for free via the App Store. MB is Megabytes
Rugged Drive via Firewire - 80 MB/s
Rugged Drvie via USB2 - 30 MB/s
Seagate Drive USB 3.0 - 160 MB/s
Mac HS2 - 97 MB/s
My principle application is backing up VMWare Fusion Virtual Machines and running them from external drives. Has been working well.
These notes reflect my hardware and experience. There is quite a bit of information about USB 3.0 and patched drivers such as the modbin PXHCD,kext patched driver. In the end, moving to new hardware and drivers was the solution.
I hope that this infomration is helpfull.