> Yes, DDR3 is the lowest CAS latency and lasts ALOT longer.

DDR5 is more reliable. Where are you getting this info that DDR3 lasts longer?

DDR5 runs at lower voltages, uses modern processes, and has on-die ECC.

This is already showing up in reduced failure rates for DDR5 fleets: https://ieeexplore.ieee.org/document/11068349

The other comment already covered why comparing CAS latency is misleading. CAS latency is measured in clock cycles. Multiply by the length of a clock cycle to get the CAS delay.