GeezerVison

DevSlp or DevSleep (sometimes referred to as device sleep or SATA DEVSLP) is a feature in some SATA devices which allows them to go into a low power "device sleep" mode when sent the appropriate signal, which uses one or two orders of magnitude less power than a traditional idle (about 5 mW,^[1] but some drives can get as low as 2.5 mW^[2]). The feature was introduced by SanDisk^[3] in a partnership with Intel.^[4] Some think that the initiative could make laptops feel like they power on basically instantaneously,^[5] while others state that this means that laptops can stay on all the time, and always be available with no adverse effects on battery life.^[6]

In traditional low-power modes, SATA link still needs to remain powered on to allow the device to receive a wake-up command. With DevSlp, rarely used 3.3 V pins of the SATA power plug will be used for the DevSlp signal instead of providing 3.3 V power. This signal can wake up the drive, and it will allow SATA link to be shut down, reducing further the power consumption.^[7]

Due to the way they work, DevSleep-enabled drives may not be suitable for most desktop PCs and some notebooks with the 3.3 V voltage present in their SATA power connectors; the presence of 3.3 V results in DevSleep-enabled drives remaining in DevSlp state.^[7] An incompatibility between a desktop mainboard and a SATA SSD may be resolved by disabling the DevSleep feature using a power connector adapter that does not pass the +3.3 V line.

• Description of device Sleep feature (DevSleep) at smarthdd.com