Dell SupportAssist Pre-Boot System Performance Check or "No Bootable Device Found": What It Means and How to Fix It

These two Dell screens are related but not the same, and it helps to know which one you are looking at.

• SupportAssist Pre-Boot System Performance Check (older Dell laptops called it ePSA, for Enhanced Pre-boot System Assessment) is Dell's built-in hardware test. It runs by itself when the laptop cannot start Windows normally, or you start it yourself by tapping F12 at power-on and choosing Diagnostics. It tests memory, the drive, the processor and other parts, then shows a result.
• "No bootable device found" (also worded as "No boot device found" or "Operating system not found") means the BIOS looked for a drive that holds a startup system and found none it can use. The cause is either a setting (boot order, boot mode, drive mode), a drive that is not detected, or a drive whose startup files are damaged.
• They often appear together. When the laptop cannot find a bootable drive, it may jump into the pre-boot check on its own, and that check may report a drive error.
• Do not panic and do not reinstall Windows yet. Your files are usually still on the drive. The first goal is to find out whether the BIOS can see the drive at all.

If the drive is visible in the BIOS, the problem is usually a setting or damaged Windows startup files. If it is not visible, think loose connection or failed drive. Everything below is ordered from the safest, easiest step to the more hands-on ones. If you want a person to look at your exact screen, you can ask a computer expert online.

• The pre-boot check is a diagnostic, not the fault. It is Dell's tool for finding the fault. Let it finish and write down what it says.
• Write down two things: the error code and the validation code shown on a failed result. Those are what Dell's support pages and any technician will ask for.
• "No bootable device" means the BIOS cannot start from any drive. It does not by itself mean the drive is dead.
• Check the BIOS first. Press F2 at the Dell logo to open the BIOS setup and see whether your SSD or hard drive is listed.
• The SATA / drive mode matters. If you or an update changed it between AHCI and RAID On (Intel RST), Windows may not find the drive. Do not change it blindly (see the careful section below).
• A drive error code means back up and replace. If the check reports the hard drive or SSD failed, the safe plan is to recover your data if possible and replace the drive.
• Disconnect everything first. External drives, USB sticks, SD cards and docks can confuse the boot order and the test.

Use the table on this page to match what you see to the likely meaning and the first fix to try. The sections below explain each step in order.

A few notes on reading the screens:

• The wording on Dell screens differs slightly between models and BIOS versions. "SupportAssist Pre-Boot System Performance Check", "Pre-boot System Assessment" and "ePSA" are the same family of test.
• The test normally shows a progress bar, then either a pass message or a failure with codes. A pass does not guarantee the boot problem is solved, since the test checks hardware, not Windows files.
• A message that says no bootable device is a BIOS message about drives. It is separate from the hardware test result.

The check is built into the laptop's firmware, so it runs even if Windows will not load. It tends to appear in two situations.

• You started it. You tapped F12 at the Dell logo and chose Diagnostics.
• The laptop started it. After repeated failed starts, or when it cannot find a bootable drive, some Dell laptops launch the check automatically.

How to let it finish properly

1. Plug in the charger. Tests can be interrupted by low battery, and a laptop running on a dying battery may fail the test for the wrong reason.
2. Do not press keys or close the lid while the progress bar runs. Some screens ask you to answer a question, such as whether you see a pattern on the display. Answer honestly.
3. Wait for it to complete. Depending on the model and options chosen, this can take from a few minutes to much longer, and it may appear slow near the end. Give it time before deciding it is stuck.
4. Write down or photograph the result. If it fails, note the error code and validation code exactly. Take a photo with your phone, since the screen will disappear after a restart.
5. Exit or restart. On a pass, exit and try a normal start. On a fail, keep the codes handy and continue to the steps below.

If the laptop keeps returning to the check, hangs on it, or restarts into it every time, work through these steps in order.

Step 1: Let one full run complete

Plug in power and let the check run to the end once. A failure with a code is useful information. A pass tells you the hardware tests fine and the issue is more likely settings or Windows startup files.

Step 2: Remove everything external

Unplug USB drives, SD cards, printers, docks and external monitors. Leave only the charger. A device that looks bootable but is not can pull the laptop into odd loops.

Step 3: Hard reset

Hold the power button for about 15 to 30 seconds until the laptop is fully off, then start it again normally. This clears a stuck state.

Step 4: Drain the flea power (a "power drain")

1. Shut the laptop down and unplug the charger and every accessory.
2. If the battery is removable, take it out. Most modern Dell laptops have an internal battery, so you leave it in place.
3. Hold the power button for about 15 to 30 seconds. This releases leftover charge in the board.
4. Reconnect only the charger, wait a minute, then turn the laptop on.

This sounds minor, but it fixes a surprising number of boot loops caused by a confused firmware state.

Step 5: Check the BIOS for the drive

Tap F2 at the Dell logo to open the BIOS setup. Look for a page listing the drives (often under system information or storage). If your SSD or hard drive is shown with its model name, the laptop can see it. If the page shows no drive, jump to the "drive not detected" notes in the next section.

Step 6: Restore BIOS defaults

In the BIOS there is a restore or load defaults option. Using it resets boot order and other settings to Dell's standard, which can clear a wrong boot setting. Save and exit afterward. Do this before changing individual options.

Step 7: Update the BIOS if you can get into Windows

If the laptop sometimes boots, update the BIOS through the Dell support site or the SupportAssist app, with the charger plugged in. Do not interrupt a BIOS update. If the laptop never boots, skip this step and use the recovery tools instead.

If the laptop overheats or shuts off during these tests, heat can be the cause. See our guide to fixing laptop overheating, which also covers Dell's own SupportAssist tools.

This is the message that sends most people searching for no bootable device found Dell or Dell SupportAssist no boot device found. The BIOS looked at every place it is set to boot from and found nothing it could start. Work down this list.

1. Check the boot sequence and boot mode

Open the BIOS with F2 and find the boot configuration page. Check:

• The boot list includes your drive. It might show as "Windows Boot Manager" or the drive's model name. If it is missing, the BIOS may not see a startable system on the drive.
• Boot mode (UEFI or Legacy). Modern Windows 10 and 11 installs use UEFI. If someone switched the laptop to Legacy mode, or the reverse, a UEFI-installed Windows will not boot. If you know you did not install Windows in Legacy mode, set it back to UEFI.
• Secure Boot. It is normally on. Leave it on unless you have a specific reason, since changing it without need can create new problems.

Change one setting at a time, save, and test. That way you know what worked.

2. Is the drive detected at all?

This is the key question. In the BIOS information or storage page, does your SSD or hard drive appear with a model name and size?

• Yes, it is listed. The hardware is connected and the problem is a setting or damaged startup files. Go on to the drive mode and recovery steps.
• No, it is not listed. The drive may be loose, failed, or running in a mode the BIOS cannot present. Do the power drain, then see the reseating step below.

3. SATA operation: AHCI versus RAID On (Intel RST), explained carefully

On many Dell laptops the BIOS has a setting called SATA Operation (or similar) with choices such as AHCI, RAID On and sometimes Disabled. This controls how the storage controller talks to the drive, and it matters more than most people expect.

• Windows was installed under one mode. Windows loads the storage driver for the mode it was installed in. If the mode is changed afterward, Windows may not have the right driver ready and can fail to start, often with a boot error or a blue screen such as "inaccessible boot device".
• The pitfall. If the setting changed from RAID On to AHCI (or the reverse) through a BIOS update, a BIOS reset to defaults, or someone trying to make a Linux or Windows installer see the drive, the existing Windows install may no longer boot, and the drive can even appear to vanish.
• What to do. If the problem began right after a BIOS reset or update, try switching the setting back to the way it was before. If you do not know what it was, try one option, save, test, and if it does not help, put it back. Do not switch modes repeatedly or reinstall Windows just to test this.
• Installing Windows from a USB stick. On some Dell models with Intel RST, the Windows installer cannot see the drive unless you load the Intel RST driver or temporarily choose AHCI. That is an installer issue, not necessarily a dead drive.

The exact names and options differ between models, so use your laptop's Dell support page or manual for the right choice. If you are unsure, this is a good point to ask a computer expert before changing more.

4. Reseat the drive, if you are comfortable

If the drive is not detected and the laptop is out of warranty (or you have confirmed that opening it will not void warranty), reseating can help. Power down, unplug, disconnect the battery connector as the Dell service manual describes, remove the bottom cover, and re-insert the SSD or drive firmly. Use an anti-static habit such as touching bare metal first. If you have never opened a laptop, skip this step and have a repair shop do it. Do not force parts.

5. Try SupportAssist OS Recovery

Many recent Dell laptops include a recovery environment. Tap F12 at the Dell logo and, if SupportAssist OS Recovery appears in the boot menu, choose it. Depending on the version, it can scan the system and offer repair or restore options. If it is not listed, your model may use a different recovery path, such as booting from a Windows recovery USB. Choose repair options before any reset option that erases files, and avoid a full reset until you have tried to back up data.

6. Use a Windows recovery USB

If you can create a Windows installer/recovery USB on another computer, boot from it with F12, choose Repair your computer, and run Startup Repair. This can rebuild damaged boot files. For related no-display and startup problems, see our guide to fixing a laptop black screen.

When the pre-boot check fails it usually shows an error code and a validation code, plus a short description of what failed. We will not guess at the meaning of specific numbers here, because the same number can mean different things on different models and BIOS versions. Instead, use the codes this way.

• Write down both codes and the service tag. The Service Tag is on a sticker on the bottom of the laptop and on the BIOS information page.
• Look up the codes on Dell's support site for your exact model, or give them to a technician. Dell's support pages decode them.
• Read the description line. It normally names the component, such as memory, hard drive, battery, or processor.
• Drive-related failures. If the result names the hard drive or SSD (for example not detected, failed a self-test, or read/write errors), treat the drive as unreliable. Back up what you can, then replace it.
• Memory-related failures. Reseating or replacing the RAM may fix it on laptops with removable memory.
• Battery or power failures. Check the charger, try another charger and look at the battery health. A weak adapter can cause boot loops.

A single failure code does not always mean the part is dead; some results come from a loose connection or a one-time glitch. Run the check a second time to see whether the same code repeats. A code that repeats is more trustworthy.

If you suspect the drive is failing, protect your data first. Every restart and repair attempt puts some stress on a failing drive.

• Back up before repairs. If you can boot even once, copy photos, documents and anything irreplaceable to an external drive or cloud storage.
• Use a recovery USB or a drive enclosure. If the laptop will not start, a technician can often remove the drive, plug it into another computer through an adapter and copy files off.
• Stop if you hear clicking. A mechanical hard drive that clicks or grinds needs professional data recovery. Further power-ons can make it worse.
• Do not choose "reset" or "reinstall" first. Those options can erase your files.

You can solve many of these problems yourself, but get help when:

• The drive is not listed in the BIOS even after a power drain and reseating. The drive, its connector or the board may have failed.
• The pre-boot check names the drive or the motherboard as failed. Plan for a replacement and data recovery.
• The laptop is under warranty. Dell may repair or replace the part at no cost, and opening the laptop yourself can complicate that. Have your Service Tag ready.
• You are not comfortable opening the laptop. Reseating a drive is simple for some people and risky for others.
• The data matters and you cannot boot. A repair shop or data recovery service is a better first step than repeated restarts.

If you want to talk it through, you can ask a computer expert online. Have the error code, validation code, model and what changed before the problem started (an update, a drop, a spill, a BIOS change). Repair costs vary widely by model, drive type and who does the work, so get a quote first. Replacing an SSD is often much less expensive than replacing a motherboard, so confirm the diagnosis before paying for the larger repair.

• Dell Support home (search by your Service Tag for your model's diagnostics, BIOS and manual pages)
• Dell LCD Built-In Self-Test (BIST) (Dell Support), a related built-in hardware test
• Your laptop's Dell service manual for the exact steps to open the bottom cover and reseat the drive.