Here's all the upgrades in my Mac Pro 4,1 : r/macpro
Review: Promise Pegasus R4i and J2i add massive storage to the new Mac Pro | AppleInsider
Promise 32TB PegasusR4i- RAID Storage MPX Module for Mac Pro (P3R4IHD32)
Apple offers PCI Express RAID Card in Mac Pro | Engadget
Mac Pro RAID setup - Paul Joy
Apple Mac Pro (Early 2009 and Mid 2010) - Mac Pro RAID Card and Battery Replacement Instructions - Mac Pro (Early 2009 and Mid 2010) - Mac Pro RAID Card and Battery Replacement Instructions
Mac Pro 4.1, 5.1 and 7.1 NVMe Raid Card Upgrade (Sonnet Fusion SSD M.2) - YouTube
2009 Apple RAID PCI Card, still useful today? - The House of Moth
Apple Mac Pro A1247 Raid Card - Computer Accessories - BMI Surplus
2009 Apple RAID PCI Card, still useful today? - The House of Moth
maxupgrades.com: MaxConnect BackPlane RAID Attachment for Mac Pro [2009 / 2010 / 2011 / 2012] with 4-Port Areca 1213-4i PCIe 2.0 6G Hardware RAID Controller with Battery BackUp
Mac Pro RAID Card: Not Too Useful | Low End Mac
The Sonnet M.2 4x4 PCIe Card adds insanely-fast SSD speeds to Mac Pro
Apple Mac Pro RAID Card(New-Open-Box) - Walmart.com