It can be annoying when an external hard drive disconnects from your computer every time it goes to sleep. This issue causes the drive to suddenly become unavailable, interrupt file transfers, and potentially lead to data loss or corruption. Having to repeatedly reconnect the drive each time the computer wakes up from sleep mode creates unnecessary hassle and frustration.
What Happens in Sleep Mode
When a computer enters sleep mode, it shifts to a low-power state to conserve energy. The computer’s state, including any open documents and applications, is saved to memory while most other components power down (https://it.wustl.edu/2022/08/hibernate-sleep-or-shut-down-what-should-i-use/). The CPU, RAM, and other key parts stay energized at a minimal level to allow for quick wake up. Peripherals like the monitor, hard drives, ports, and network connection are powered down.
So when sleep mode is activated, the computer screen and any external devices like a hard drive will turn off. But the computer retains enough power to monitor for a wake-up signal, while using just 1-5% of full power (https://www.dell.com/support/kbdoc/en-us/000130380/how-to-wake-a-computer-or-monitor-from-sleep-suspend-or-hibernate). This allows the computer to resume where it left off almost instantly once woken up.
However, external devices like hard drives that are powered through the USB connection will be cut off from power in sleep mode. This can cause them to disconnect since the ports are suspended.
USB Power Management
Windows includes a USB power management setting that can turn off power to USB ports during sleep mode to conserve energy. This setting is enabled by default in Windows 10 and 11. When USB power is disabled in sleep mode, external hard drives and other USB devices will disconnect since they are not receiving power.
According to Microsoft, “To prevent devices from disconnecting, disable USB selective suspend for that device.” [1] With USB selective suspend disabled for a device, Windows will not power down its USB port in sleep mode.
To prevent a hard drive from losing power and disconnecting in sleep mode, the USB power management setting needs to be changed. This can be done through the Power Options in Windows. By disabling “USB selective suspend setting” for a specific device, that USB port will remain powered in sleep mode and prevent disconnection.
Insufficient Power
One of the most common reasons an external hard drive may disconnect when your computer sleeps is because of insufficient power delivery over the USB connection [1]. USB ports provide limited power, usually up to 500mA. Many external hard drives require more than this to operate properly, especially mechanical hard drives with spinning platters that need consistent power.
When your computer is awake, the USB port provides enough steady power to keep the drive connected. But when the computer goes to sleep, it enters a low-power state which reduces or interrupts the power delivery over USB. If the drive requires more power than the USB port can provide in this state, the drive will disconnect due to insufficient power.
This problem can be exacerbated if using a USB hub without its own external power supply. Connecting multiple devices through an unpowered hub splits the limited USB power budget among all the devices, leaving even less power available for each one. So an external drive connected through a hub is more likely to experience disconnects due to insufficient power when the computer sleeps.
The best solution is to connect the external drive directly to a rear USB port on the computer if possible, avoiding hubs. If using a hub is necessary, choose one with its own power supply to ensure steady power delivery to all connected devices.
Drive Settings
Some external hard drives have power saving settings enabled by default that can cause the drive to disconnect when the computer goes to sleep. For example, Western Digital (WD) external hard drives come with a feature called WD Sleep Mode which will spin down the disk after a period of inactivity to conserve power.
To prevent disconnections, you may need to disable sleep settings like WD Sleep Mode in the device’s software utility or settings panel. According to WD, “Disabling WD Sleep Mode may help prevent the attached drive from powering down unexpectedly when the PC is still actively reading and writing data”
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Seagate external drives also have similar settings like Seagate Power Save that can be disabled. Check your drive manufacturer’s instructions on where to locate and how to disable these types of sleep functions that are designed to save power but may inadvertently cause disconnects[1].
Outdated Drivers
Outdated drivers for the USB port or the external hard drive itself are a common source of connectivity issues with external drives. Drivers act as software interfaces between the operating system and the hardware device, providing the necessary code for them to communicate properly. However, as operating systems update, new drivers are required for hardware to function optimally.
If you are using older, incompatible drivers, the operating system and the external drive may struggle to maintain a stable connection. Signals get crossed, connections get interrupted, and the drive is prone to random disconnection, especially coming out of sleep mode. Updating to the latest USB and external drive drivers from the device manufacturer will resolve these software and hardware communication problems.
Damaged Cables
One of the most common reasons an external hard drive may disconnect when your computer sleeps is a damaged USB cable. USB cables degrade over time from bending and twisting. This can cause interruptions in the flow of power and data between the drive and computer. Damaged cables may have visible fraying, cracks, or severed internal wires. However, damage can also happen internally without any external signs. Using low-quality or improperly shielded USB cables also increases the likelihood of disconnection issues.
When your computer sleeps, it enters a low-power mode which reduces energy sent through USB ports. If the USB cable is damaged, this lower power delivery can be insufficient to maintain a steady connection. The cable is no longer capable of transmitting enough power and data to keep the drive connected. This results in the external drive unexpectedly disconnecting whenever your computer goes to sleep.
To prevent disconnections, inspect USB cables for any visible damage. Try swapping in a high-quality cable designed for data transfer, rather than a cheap generic cable. Proper shielding and gauging of power and data wires in cables engineered for external drives can improve connectivity issues. If drive disconnections persist after cable replacement, the problem may lie with other factors like port damage or power settings.
Interference
One potential cause of external hard drives disconnecting when the computer sleeps is wireless interference. Many external hard drives use the 2.4 GHz band to communicate with the computer, which is the same frequency used by Wi-Fi routers, Bluetooth devices, cordless phones, and other electronics. The USB 3.0 standard, in particular, is known to produce radio frequency interference on the 2.4 GHz band (Source). When the computer goes to sleep, the interference may disrupt the connection between the external drive and the computer, causing the drive to disconnect.
There are a few solutions to try if wireless interference is the culprit. Using a USB extension cable to increase the distance between the external drive and the computer’s USB port may help reduce interference. Connecting the drive to a USB 2.0 port instead of 3.0 can also mitigate the problem, although at the cost of slower transfer speeds. Proper placement of the drive, away from the Wi-Fi router and other electronics, could reduce disruption as well. Upgrading to a 5 GHz Wi-Fi network moves the router’s transmission away from the 2.4 GHz band used by external drives. As a last resort, using a USB hub with its own dedicated power supply can ensure consistent power delivery to the drive despite any wireless interference.
Troubleshooting
There are several troubleshooting steps you can take if your external hard drive keeps disconnecting:
- Try using a different USB port on your computer. The port may be damaged or not providing enough power.
- Inspect the USB cable for any damage and replace it if necessary. Damaged cables can cause connectivity issues. Some high-quality USB 3.0 cables are recommended for reliability (
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- Adjust your power settings so USB ports remain powered even in sleep mode. Go to Control Panel > Hardware and Sound > Power Options > Change Plan Settings > Change Advanced Power Settings > USB Settings to make changes.
- Disable USB power management in Device Manager if the hard drive disconnects from a specific port. Right click on the USB root hub for that port and uncheck “Allow the computer to turn off this device to save power.”
- Try connecting the drive to a powered USB hub if you suspect power delivery issues.
Following basic troubleshooting steps can often resolve random disconnection issues with external hard drives.
Preventing Disconnections
There are a few things you can try to prevent your external hard drive from disconnecting when your computer sleeps:
- Allow your external drive to wake the computer from sleep mode. Go to Control Panel > Hardware and Sound > Power Options > Change Plan Settings. Click “Change advanced power settings” and expand the USB settings. Set “USB selective suspend setting” to Disabled.
- Use a powered USB hub. This provides consistent power to the drive even when your computer goes to sleep.
- Update your USB and external hard drive drivers to the latest versions. Outdated drivers can cause connectivity issues.
- Adjust when your computer and hard drive go to sleep. Increase the times so they don’t sleep as quickly when idle. You can change these settings in Power Options.
- Try connecting your external drive to a different USB port on your computer. Some ports may provide more consistent power.
- Inspect the USB cables and connections. Damaged or loose cables can interrupt the connection when computer goes to sleep.
- Keep the drive and cables away from other USB devices or charged electronics. This can reduce interference.
If you’ve tried these troubleshooting tips and are still experiencing disconnections, there may be a larger issue with power management, drivers, or the hard drive itself.
