Can power to SSD be switched off?

I have installed a WD Blue 3D NAND Internal PC SSD - SATA III drive into my desktop computer, and I need a convenient way to disable the SSD so that when I boot the computer from a USB flash drive, the SSD is not accessible and cannot be infected by a virus. There is no option in the BIOS setup to disable SATA, so I’m thinking of installing a switch to open the +5 volt red wire going to the power connector on the drive. I would not use this switch while the computer is on, only when it is off. The idea is to disable the SSD before booting from a USB flash drive.

My question is, can the power to the SSD be turned off while leaving the SATA data cable plugged in, without damaging the SSD? That would be equivalent to unplugging the power cable while leaving the SATA data cable plugged in.

SSD power consumption is automatic and it usually is elevated only with writes, otherwise its using minimal power.

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I’ve thought of a better solution. The SATA 3.3 spec uses pin 3 on the power connector as a power disable feature. When it is driven to a logical high (around +3 volts), the drive powers down. This is implemented in the Western Digital SSD SATA III drive, according to the User Manual, which calls it DEVSLP and says “Device sleep, high signal driven by the host to shut down the SATA interface completely.” SATA power pin 3 was formerly used to supply +3.3 volts, but now on most SATA power connectors the orange wire for +3.3 volts is missing, as in my computer. All I have to do is obtain a SATA power connector that has the orange wire, splice the black, red, and yellow wires to the existing cable, and rig the orange wire to a switch that supplies +3 volts. Closing the switch should then power the SSD down, and opening the switch should let it power up.

Why not make it simple…Get a swapable drive bay and a 3.5 to 2.5 adapter. Then simply pull the SSD out of the bay prior to boot.


I use this method to boot from many different drives each with a different OS on it. Like Windows 10 on one and Android X86 on another.

I could do that, but I’ve already ordered the SATA power cable and am looking forward to rigging the switch. I think pulling the drive in and out a lot could wear the contacts, and it is easy to just flip a switch.

UPDATE: Powering the computer on with +3.3 volts on pin 3 of the SATA power connector on the SSD does not disable the drive. My guess is that the drive has to be already powered up and for pin 3 to be transitioned from logic 0 to logic 1 in order for DEVSLP to be activated. The reason for that would be to prevent DEVSLP being activated at startup when the SATA power connector has the orange wire which connects +3.3 volts from the power supply. That has been a problem for some SSDs in the past.

I noticed that devices are offered on which switch power on or off to SATA disk drives in order to enable and disable them. It does that while leaving the SATA data cables connected to all drives in the computer. Apparently, that does not harm the drive. So, I rigged a switch in series with the red +5 volt wire to the SSD, and that works. If I open the switch when the computer is off, the SSD will not be active or accessible when the computer is turned on. To avoid unstable startup and possible data loss, I turn the switch back on only when the computer is off.