HighPoint RocketRAID 2720GL with OWC SAS/SATA Link For 2006-08 Mac Pro Systems.

Go from SATA 2.0 to 3.0 on the internal had drive bays but using this card in conjunction with the mini-SAS extender cable and adapter.

Instructions for this modification can be found here:

https://eshop.macsales.com/blog/12247-upgrade-your-06-08-mac-pros-internal-bays-to-sata-3-0/

Originally purchased the cable and adapter from OWC as MaxUpgrades MaxConnect SAS/SATA Link for 2006-2008 Max Pro Systems.