> You're only accounting for the RAM power. Accessing the SSD costs power, too. A typical modern SSD reads at 500 MiB/s, consumes 3 watts when reading, and 0.3

> You're only accounting for the RAM power. Accessing the SSD costs power, too. A typical modern SSD reads at 500 MiB/s, consumes 3 watts when reading, and 0.3 watts when idle. A stick of DDR3 RAM consumes about 3 watts, just sitting idle. The power consumption from prefetching is minor compared to that of the RAM.