From Amazon review:
I bought this and a Samsung 840 EVO 1TB SSD to bump the speed of main drive in my 2010 Mac Pro. I replaced a Crucial 512GB M4 SSD running on the Mac Pro's internal 3Gb/s SATA controller. I installed the Sonnet Tempo in the PCIe slot right next to the graphics card (labeled an x16 slot). Because I have extra wires running through that area to power my GTX 780, I didn't install the second drive extension on the Sonnet. I did test fit it though and it looks like it'll fit just fine if you want 2 SSDs installed on the Sonnet.
I used SuperDuper to clone my boot drive to the Samsung. I had to update the Sonnet Tempo's firmware to get it to boot from it though on my Mac Pro. The firmware update was easy though (get it from Sonnet's website). After updating the firmware, I set it as the boot drive in System Preferences/View/Startup Disk. Everything is working great now.
Blackmagic Disk Speed Test (from the Mac App Store) reports 460MB/s write and 497MB/s read speeds. That's twice what the internal 3Gb/s SATA was doing. The Sonnet + Samsung reported 350/450 when installed in a x4 PCIe slot. I didn't do much testing with the Sonnet installed in that slot, but that may be something to dig into deeper if you need to install the card on a non-x16 slot.
Overall, this is a great way to boost the drive speed if your system only has 3Gb/s SATA like my Mac Pro. For $120, this is a must buy of you have an SSD.
Itching to try...
Jim? Any thoughts.