iFixit.com - Larger modules in the Mac Pro —like RAM and some PCIe cards—can be swapped without tools, almost Lego-style. Apple even provided step numbers and diagrams for certain repairs right on
Samsung 970 EVO SSD runs hot on Mac Pro 6,1 | MacRumors Forums
1GB Mac Pro Memory Upgrade DDR3 PC3-8500 DIMM - 661-5002
OWC 32.0GB Mac Pro / Xserve 2009 Memory Matched Set... at MacSales.com