Most benchmarks I’ve seen show DDR5 at around 90-100 ns latency and LPDDR5X-7500 at around 110-130 ns with the AMD 7040/8040 series memory controller.
Here are several examples that I picked randomly (well the Framework laptops were deliberate) from the NotebookCheck website (to the best of my knowledge all the devices listed here have the same AMD memory controller):
- Razer Blade 14: DDR5-5600 → 89.9 ns
- Framework Laptop 13: DDR5-5600 → 90.0 ns
- Framework Laptop 16: DDR5-5600 → 91.4 ns
- Lenovo LOQ 15APH8: DDR5-5600 → 92.4 ns
- HP EliteBook 845 G10: DDR5-5600 → 92.6 ns
- Asus Zenbook 14 OLED: LPDDR5X-7467 → 114.5 ns
- Lenovo Legion Go: LPDDR5X-7500 → 119.5 ns
- Lenovo Z16 Gen 2: LPDDR5X-6400 → 121.3 ns
- Minisforum Mercury Series EM780: LPDDR5X-6400 → 130.1 ns
- Lenovo Thinkpad P16s Gen 2: LPDDR5X-6400 → 133.4 ns
SODIMM also has the advantage of 2 slots being typical (vs 1 with LPCAMM). That opens up the flexibility to only fill one slot initially and fill the other later (not great for dual channel reasons, but DDR5-5600 is fast enough to not bottleneck a CPU too badly so it is reasonable to do in systems with a dGPU).