3 Things to Know About RAM Ranks in the 2013 Mac Pro

All four RAM slots must use the same rank configuration The 2013 Mac Pro requires either all single-rank or all dual-rank sticks. Mixing ranks can cause boot failures or throttled performance.

You need registered ECC (RDIMM) at 1866 MHz Standard unbuffered ECC won’t work. Check your sticks for markings like 1Rx4 or 2Rx4 to confirm they’re the right type.

Buy a matched kit from a trusted vendor Avoid guessing with random sticks. OWC sells kits confirmed compatible with the Mac Pro, saving you time and frustration.