An external hard drive or internal computer drive may fail to appear in File Explorer (Windows) or Finder (macOS) upon connection or system startup. A hard drive not showing up is a common and disruptive issue preventing access to important files. This problem affects both internal and external drives across Windows and Mac systems.
The causes for this issue range from simple configuration problems to serious hardware failures. This guide outlines a systematic troubleshooting approach, beginning with basic checks and emphasizing data safety at every step.
Why Is My Hard Drive Not Showing Up?
A hard drive might not show up due to various reasons: simple connection issues (cables, ports), power problems (especially external drives), missing drive letters in Windows, unmounted volumes in macOS, file system corruption (appearing RAW), partition table loss (unallocated), or serious hardware failure (drive not detected in BIOS/UEFI).
Step 1: Checking Drive Detection at Hardware Level (BIOS/UEFI)
Before troubleshooting within the operating system, we need to see if the computer’s fundamental input/output system (BIOS or UEFI) even recognizes that the hardware exists. If the drive is not detected here, it certainly won’t show up in Windows or macOS.
How to Check BIOS/UEFI
- Restart your computer.
- Enter Setup: As it boots, press the key indicated on screen to enter Setup, BIOS, or UEFI. Common keys include Del, F2, F1, F10, F12, or Esc. You may need to look up the specific key for your motherboard manufacturer.
- Look for Drive Information: Navigate through the menus (often under sections like “Boot,” “Storage,” “SATA Configuration,” or “System Information”). Look for a list of connected SATA or NVMe drives.
- Check Boot Order: Also, check the boot sequence/order. Is your primary hard drive listed and set as the first boot device (unless you intend to boot from USB/DVD)?
Verify Specific BIOS/UEFI Settings
SATA Port Status: Navigate menus related to SATA Configuration, Storage Configuration, or Integrated Peripherals. Find the list of SATA ports (Port 0, Port 1, etc.) and ensure the specific port your drive is connected to is Enabled. Sometimes ports can be individually disabled.
SATA Controller Mode: Look for settings like “SATA Mode,” “Configure SATA as,” or similar. Common options are AHCI, RAID, or IDE (Compatibility). While mainly affecting bootability and performance, ensure it’s set appropriately (usually AHCI for modern single drives) as an incorrect setting might rarely impact detection in some specific BIOS/motherboard combinations.
What If Hard Drive Is Not Detected in BIOS/UEFI?
If the drive is completely absent from the BIOS/UEFI list:
- Check Physical Connections (Internal Drives – Use Caution): If you are comfortable working inside your computer case and understand static discharge precautions, power off completely, unplug the computer from the wall outlet, and ground yourself before touching internal components. Carefully check that both the SATA data cable is securely plugged into the drive and the motherboard SATA port, and the SATA power cable from the Power Supply Unit (PSU) is firmly connected to the drive. Reseating both cable ends carefully can sometimes resolve connection issues. If using an NVMe SSD, ensure it is properly seated in its M.2 slot. If unsure about performing these checks safely, skip this step and seek professional assistance.
- Check Power (External Drives): Ensure the external drive’s power adapter (if it has one) is plugged in and functional. Try a different wall outlet. Ensure the USB cable is firmly connected at both ends. Try a different USB port on your computer.
- Listen/Feel for Spin-Up: Does the drive make any sound or vibrate when power is applied? If it remains completely silent and still, it might not be receiving power or could have a critical failure like a seized motor or dead PCB. Refer to our guide if your Hard Drive Is Not Spinning.
- Potential Hardware Failure: If connections and power seem okay, but the drive is still not detected in BIOS/UEFI, it strongly suggests a serious hardware issue with the drive itself (PCB failure, internal mechanical/electronic failure) or potentially the motherboard port. Further DIY troubleshooting is highly risky. Data recovery requires professional intervention at this stage.
Why Isn't My Hard Drive Showing Up in Windows/Mac (Even if Detected in BIOS)?
If BIOS detects the drive but the OS doesn’t show it, common reasons include: the drive isn’t initialized, it lacks a drive letter (Windows), the volume isn’t mounted (Mac), the file system is corrupted (RAW), or the file system format isn’t supported by your current OS.
Step 2: Detected in BIOS, But Not Showing Up in the OS? (Checking Disk Management/Disk Utility)
If the drive is listed in the BIOS/UEFI but still doesn’t appear in File Explorer or Finder, the issue likely lies within the operating system’s configuration or the drive’s logical structure. We need to use the OS disk management tools.
Using Disk Management (Windows)
- Right-click the Start button (or press Win + X).
- Select “Disk Management.”
- Look for your drive in the list (usually displayed as “Disk 0”, “Disk 1”, etc., in the lower pane).
Using Disk Utility (macOS)
Go to Applications > Utilities > Disk Utility.
Ensure “View” (in the top menu bar or top-left corner) is set to “Show All Devices.”
Look for your drive listed in the left-hand sidebar (it might show the manufacturer name or connection type like USB).
What to Look For in Disk Management / Disk Utility
Even if the drive doesn’t appear with a letter or volume name, it might show up here in one of these states:
- Healthy, but No Drive Letter (Windows): The partitions are listed with file systems (NTFS, FAT32), but no drive letter (like D:, E:) is assigned.
- Not Initialized / Unknown / Unallocated: The drive is listed, but the space shows as “Not Initialized” or completely “Unallocated.” This often happens with brand new drives or drives whose partition table is corrupted.
- RAW File System: A partition is listed, but the file system type is shown as “RAW.” This indicates file system corruption.
- Listed but Not Mounted (macOS): The drive or its volumes appear in Disk Utility but are greyed out, indicating they are not mounted (made accessible).
- Foreign Disk (Windows Server/RAID): Indicates a disk that was part of a different system’s dynamic disk or RAID setup.
Step 3: Addressing Common OS-Level Issues (Proceed with Caution!)
If your drive appears in Disk Management or Disk Utility but not File Explorer/Finder, here are common reasons and potential actions.
Some actions, like initializing or formatting, WILL ERASE DATA. Proceed only if you are certain the drive contains no needed data or after successful data recovery.
Assigning a Drive Letter (Windows)
- Problem: Drive is healthy and formatted but lacks a drive letter.
- Action (Relatively Safe): In Disk Management, right-click the partition (the healthy volume), select “Change Drive Letter and Paths…”, click “Add”, choose a letter, and click OK.
- Risk: Minimal risk if the partition is healthy.
Mounting a Volume (macOS)
Problem: Drive/volume appears in Disk Utility but is greyed out (unmounted).
Action (Relatively Safe): Select the greyed-out volume (not the parent drive) in Disk Utility and click the “Mount” button in the toolbar. If it mounts successfully, it should appear in Finder.
Risk: Minimal risk if the underlying file system is healthy. Failure to mount often indicates corruption. For more Mac-specific troubleshooting, especially with external drives, see our dedicated post: External Hard Drive Not Showing Up.
Initializing a Disk (Windows/macOS - DATA LOSS RISK!)
Problem: Drive shows as “Not Initialized” or “Unknown.” Often occurs with new, blank drives.
Action (ERASES DATA): In Disk Management, right-click the disk name (e.g., Disk 1) and choose “Initialize Disk.” Select a partition style (GPT is modern standard, MBR for older compatibility). On Mac, Disk Utility might prompt to initialize or use “Erase” on the parent drive. THIS WIPES ALL EXISTING DATA.
Guaranteed data loss if the drive wasn’t blank. Only do this for brand new drives or if you’ve already recovered needed data professionally. If a previously working drive suddenly shows as uninitialized, it likely indicates severe partition table corruption requiring data recovery before initialization.
RAW File System / Corruption (DATA LOSS RISK!)
Problem: Drive/partition shows as RAW or fails to mount due to corruption. Windows/macOS might prompt you to format it.
Action (DO NOT FORMAT): Formatting a RAW drive will erase the data. Standard repair tools (chkdsk, Disk Utility First Aid) are risky and can worsen data loss (see previous posts). The safest path is professional data recovery..
Unsupported File System
Problem: Drive is formatted with a file system your current OS doesn’t natively support (e.g., Linux Ext4 on Windows/Mac, macOS APFS on Windows).
Action: Use a computer with the compatible OS, or install third-party software/drivers that enable reading the file system (use reputable sources). Formatting is not required if you just need read access on an incompatible system.
Internal SSD Specifics
Modern NVMe SSDs sometimes require specific drivers or BIOS settings (like NVMe mode enabled). If an internal SSD isn’t showing up, check motherboard manufacturer support for driver/BIOS updates.
Step 4: Recognizing Signs of Physical Failure
If the simple logical fixes above don’t work, or if you observe other symptoms, physical failure becomes more likely:
- Drive Not Detected in BIOS/UEFI: As discussed in Step 1, this usually points to hardware issues.
- Clicking, Grinding, Beeping: Any unusual noises indicate mechanical failure requiring immediate power-off and professional help.
- Drive Disappears Intermittently: The drive might show up sometimes but vanish during use, suggesting failing components or connection issues.
- Very Slow Performance: Extreme sluggishness before it stopped showing up can indicate developing bad sectors or failing heads.
- S.M.A.R.T. Warnings: If you previously received drive health warnings from monitoring tools.
If physical failure is suspected, stop all troubleshooting attempts immediately to prevent further damage.
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When Professional Data Recovery is the Necessary Path
DIY has limits. Professional data recovery is needed if:
The drive is not detected in BIOS/UEFI.
The drive makes physical noises.
The drive shows RAW or uninitialized/unallocated, containing critical data.
Simple fixes fail, and data is valuable.
You suspect physical damage.
You are uncomfortable with technical steps.
Professionals use specialized tools and cleanrooms to maximize recovery chances safely when your computer not detecting hard drive is due to severe issues. Details: Hard Drive Data Recovery Service Page).
Preventing Future "Not Showing Up" Issues
Good practices help:
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Safely Eject Drives before unplugging.
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Use Quality Cables/Power Supplies.
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Protect from Shocks.
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Monitor Drive Health (Basic S.M.A.R.T.).
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Maintain Backups (essential protection).
Get a Free Consultation.
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Conclusion: Systematic Checks and Prioritizing Data
A hard drive not showing up can range from simple fixes to hardware failure. Systematically check BIOS/UEFI, then OS disk tools to diagnose the cause. Prioritize data safety: Avoid destructive actions (initializing, formatting, risky repairs) on drives with important data, especially with corruption or hardware issue signs. If the drive is physically failing, not detected at boot, or contains critical inaccessible data, professional data recovery is the safest approach. Explore our Overview of Common Hard Drive Problems for more context.
Frequently Asked Questions
Why is my external hard drive not showing up on my Mac but works on Windows?
This is almost always due to file system incompatibility. The drive is likely formatted as NTFS (Windows standard), which macOS can read but not natively write to without third-party software. Reformatting as exFAT makes it compatible with both, but erases data. Alternatively, use macOS NTFS driver software.
My hard drive shows up in Disk Management as "Unallocated." Can I get data back?
Possibly, but do not create a new volume or format it. “Unallocated” means the partition information is gone. Data might still physically exist but requires professional recovery tools to scan the raw space and rebuild the lost partition structure or carve files directly.
Can updating drivers fix a hard drive not showing up?
Sometimes, especially for specific storage controllers or external devices, an outdated or corrupted driver can cause detection issues within the OS (even if seen in BIOS). Updating motherboard chipset drivers or specific device drivers can help in some cases, but it’s less common for simple non-detection than partition/file system issues or hardware failure.
My new hard drive isn't showing up. What did I do wrong?
Usually nothing! New drives often ship uninitialized and unformatted. You typically need to go into Disk Management (Windows) or Disk Utility (macOS), initialize the disk (choose GPT partition style), and then create and format a new volume/partition before it will appear in File Explorer/Finder.
Is it safe to assign a drive letter if Disk Management shows the partition as healthy?
Generally, yes. Assigning a drive letter in Windows is usually a safe, non-destructive operation if Disk Management correctly identifies the partition and its file system (e.g., NTFS, exFAT).
