Write caching should always be enabled but especially with SSDs, they're designed with it in mind, for both performance and endurance. Write deferment improves endurance for two reasons: one, it reduces unnecessary writes (lower write amplification) and two, it writes sequentially (not randomly) which also reduces NAND wear. Nowadays consumer drives have SLC caching - portion of the TLC in single-bit mode - so this is a bit more complicated, but that's the general idea. For performance it's also improved because it can have optimal parallelization (esp. important for SSDs vs. HDDs). SSDs also rely on DRAM (and/or SRAM) for the flash translation layer (FTL) which handles metadata (data about data - mapping/addressing, garbage...