DDR5 "training" helps optimize RAM for improved performance without causing instability.

Memory training mainly affects high-performance DDR5 with special profiles like XMP and EXPO.

Memory training may cause a delay in boot time for new PCs, but it's a normal and beneficial process.

If you've just put together a new computer system, and it's taking forever to actually boot, don't panic! While you may have forgotten to plug something in, if it's a DDR5-powered computer you may just be encountering memory training.

DDR5 "training" is a type of memory calibration. It's a way for your motherboard and CPU memory controller to figure out how to get the most out of your RAM without causing instability.

DDR5 has a lot of complex under the hood improvements over DDR4, and there are an infinite combination of components possible in a given PC, so training lets the computer pick the right voltage, frequency, timing and other tunable specs for those specific memory modules. After all, there can be differences between otherwise identical RAM modules, which is one of the reasons they are usually sold in pairs that were manufactured sequentially.

Memory training isn't exclusive to DDR5 memory, it also happens with DDR4. It's also not a long process with all DDR5. It's mostly high-performance DDR5 with special high-performance profiles such as XMP and EXPO that require extensive training before the right optimal settings are found. Also, if you have a lot of memory modules in the system, that can affect things as well.