What Actually Decides a Gen 5 Drive's Performance

Three things separate one PCIe 5.0 drive from another, and the sequential number on the box is the least useful of them. The first is the controller: the earliest Gen 5 designs hit their figures at a power draw that demanded a fan, while the current 6nm-class silicon reaches comparable throughput at markedly lower power, and a newer cache-free variant now gets close again without onboard DRAM. The second is the memory layout, because more packages working in parallel is what holds a write rate up once the fast cache has been used. The third is the slot you put it in.

That last point catches most upgrades. On the majority of consumer boards only the M.2 slot wired directly to the processor runs at PCIe 5.0; the rest sit behind the chipset at Gen 4. Populating the fast slot can also drop the graphics card from sixteen lanes to eight on some designs, which the manual will state and the box will not. A drive dropped into a Gen 4 slot works perfectly and simply negotiates down, so the money is what gets wasted rather than the hardware.