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Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →A blue screen that names asmtxhci.sys usually implicates the ASMedia USB 3.x extensible host-controller driver path, but the filename alone does not prove that the driver is the only cause. A recently connected USB device, a damaged cable or hub, outdated controller firmware, BIOS compatibility, or other software can trigger the same crash. Start with reversible checks—disconnect new USB hardware, use Safe Mode if Windows is unstable, and identify the exact controller—before changing drivers or firmware.
What asmtxhci.sys means
asmtxhci.sys is the filename associated with an ASMedia USB 3.x extensible host-controller driver. The host controller is the hardware and driver layer that manages USB 3.x ports, including traffic between Windows and connected devices. You may see the filename with stop codes such as SYSTEM_SERVICE_EXCEPTION, or the blue screen may simply report that Windows encountered a problem and collected diagnostic information.
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The name is a clue, not a verdict. Microsoft explains that a blue screen can be caused by a hardware device, its driver, or software. A peripheral that exposes a controller defect can therefore produce a crash that appears to implicate asmtxhci.sys, even when replacing the driver is not the complete answer.
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Before changing anything
- Write down the stop code, the time of the crash, and what was connected or changed immediately beforehand.
- Save important work and, if Windows is still usable, back up files before BIOS or firmware work.
- Keep a working keyboard and mouse connected. If they use USB, leave those devices attached while you remove optional hubs, storage, phones, cameras, printers, docks, and other recently added hardware.
- Do not install a driver intended for a different motherboard, computer model, add-in card, or Windows edition simply because its filename looks similar.
Fix the crash in the safest order
1. Disconnect recently added USB hardware and restart
Power down normally if possible. Remove any USB device, hub, dock, adapter, or cable that was added shortly before the blue screens began. If you cannot identify the new item, disconnect nonessential USB hardware and leave only the input devices needed to operate Windows. Restart and use the computer long enough to determine whether the crash returns.
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This test is deliberately simple and reversible. If the blue screen stops, reconnect devices later one at a time. The first device that brings the crash back becomes the leading suspect; test it with a known-good cable and a different USB port before deciding that Windows itself is damaged.
2. Use Safe Mode when normal Windows will not stay running
Safe Mode loads a limited set of drivers, which can let you remove a conflicting device or inspect the system without repeatedly triggering the full USB stack.
- In Windows 11, open Settings > System > Recovery. In Windows 10, open Settings > Update & Security > Recovery.
- Under Advanced startup, select Restart now.
- At the recovery menu, choose Troubleshoot > Advanced options > Startup Settings > Restart.
- After the restart, press 4 or F4 for Safe Mode. Choose 5 or F5 for Safe Mode with Networking only when you specifically need network access.
If Windows cannot reach Settings, interrupt startup two or three times by holding the power button during the boot process. Windows should enter its recovery environment, where the same Troubleshoot > Advanced options > Startup Settings path is available. Avoid repeated forced shutdowns once recovery appears.
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3. Record the stop code and module context
In normal mode or Safe Mode, open Event Viewer by searching for it from Start, then select Windows Logs > System. Review entries created at the crash time and note the stop code, the named module, and whether a USB device or driver installation appears immediately before the failure. If your Windows configuration creates crash dumps, examine the dump details for the same context rather than relying on the filename shown on one blue screen.
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Keep the notes. If a later driver update changes the symptom, the original stop code and timing help distinguish a new problem from a partial fix.
4. Identify the ASMedia controller in Device Manager
- Right-click Start and open Device Manager.
- Expand Universal Serial Bus controllers.
- Look for an entry naming an ASMedia USB 3.x or USB 3.0 eXtensible Host Controller. The exact wording varies by Windows version and motherboard.
- Open Properties, check the Driver tab, and record the provider, date, version, and whether Windows reports a problem.
If no ASMedia entry is visible, check for an Unknown device or a warning icon under USB controllers. A missing or corrupted driver can prevent Windows from displaying the controller with its expected name.
5. Install the exact driver from the computer or motherboard maker
For a built-in controller, use the support page for the exact computer or motherboard model. For a USB controller on an add-in card, use the card manufacturer’s support page. Select the package for your Windows version and system architecture, then follow that vendor’s installation instructions and restart.
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Microsoft directs users to the PC or add-in-card manufacturer for host-controller updates because the package may include model-specific settings and compatibility fixes. A generic package can be signed and still be wrong for a particular board.
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The Microsoft Update Catalog lists an ASMedia Technology Inc USB 3.0 eXtensible Host Controller driver, version 1.16.56.1, dated March 25, 2019, for Windows 10 version 1809 and later. That listing shows that a signed ASMedia package exists; it is not evidence that version 1.16.56.1 is the correct choice for every motherboard or for Windows 11. Prefer the OEM package whenever one is available.
6. Roll back when the crashes began after an update
If the timing points to a recent driver update, return to the previous package:
- In Device Manager, open the ASMedia controller’s Properties.
- Select the Driver tab and choose Roll Back Driver.
- Choose a reason when Windows asks, confirm, and restart.
The rollback button may be unavailable if Windows has no previous package. Do not force a rollback by installing an unrelated driver; use the OEM support page to obtain the model-specific earlier version instead.
7. Disable or uninstall the controller as a diagnostic test
When updating does not help, Microsoft recommends disabling or uninstalling the device as a diagnostic step. In Device Manager, right-click the ASMedia controller and select Disable device, then restart and observe whether the blue screen stops. Disabling the controller can make some USB 3.x ports unavailable, so keep a non-USB input method available if your computer supports one.
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If disabling changes the behavior, return to Device Manager and use Uninstall device. If Windows offers to remove the driver package, select that option only when you have the correct OEM installer saved locally. Restart, then install the OEM package or use Action > Scan for hardware changes to let Windows rediscover the controller. Uninstalling is more disruptive and less reversible than disabling, so use it after the safer tests.
8. Check BIOS and USB-controller firmware
Outdated BIOS or controller firmware can cause USB 3.x compatibility and routing problems. Visit the support page for the exact computer, motherboard, or add-in card and look specifically for BIOS, UEFI, or USB-controller firmware updates. Read the release notes to confirm that the update applies to your model and Windows configuration.
- Use the manufacturer’s model identifier, not a family name that covers several boards.
- Connect stable power; do not interrupt a BIOS or firmware write.
- Follow the vendor’s recovery instructions and record current BIOS settings if the update may reset them.
- After the update, load Windows with only essential USB devices attached and test before reconnecting a full setup.
Microsoft notes that a BIOS update can resolve USB 3.x compatibility or routing issues. Firmware work carries more risk than a driver rollback, so it belongs after device isolation and the correct driver check unless the manufacturer specifically identifies a known urgent fix.
9. Reconnect devices one at a time
Once the controller driver and firmware are current, shut down or restart and reconnect peripherals individually. For each device, test a direct motherboard port before using a hub or dock. Try a known-good cable and, where available, a different USB generation or port. Keep notes on which combination is stable.
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A single peripheral, cable, or hub can expose a controller or firmware defect. If one item reliably reproduces the crash while other devices work, replace or repair that item rather than repeatedly reinstalling the controller driver.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to choose the next remedy
| Remedy | Reversibility and risk | Primary scope | Best source or compatibility check |
|---|---|---|---|
| Disconnect a new device | Fully reversible; lowest risk | One peripheral, cable, hub, or dock | Test known-good ports and cables |
| Driver rollback | Usually reversible; lower risk than uninstalling | Recent controller-driver change | Previous OEM package or the Roll Back Driver button |
| OEM driver update | Reversible by rollback; moderate change | Controller software and model-specific compatibility | Exact PC, motherboard, or add-in-card manufacturer |
| Disable or uninstall | More disruptive; USB 3.x ports may stop working temporarily | Controller software and detection | Keep the correct installer before uninstalling |
| BIOS or controller-firmware update | Higher risk if interrupted; settings may reset | Firmware, routing, and platform compatibility | Exact model support page and release notes |
| USB 3.0 PCIe expansion card | Physical change; last resort | Replacement host controller | Available PCIe slot, operating-system support, and required USB speed |
What to do when the crash persists
If disconnecting USB devices changes nothing
Work through the driver evidence again: confirm the controller entry, compare the installed provider and version with the exact OEM package, and test rollback or disablement. If Safe Mode is stable but normal Windows crashes, the difference points toward a driver or software interaction loaded during a normal boot rather than proving that the hardware is defective.
If only one port or device triggers the blue screen
Stop using that port or device while testing. Try a different port on the same computer, a direct connection instead of a hub, and a known-good cable. A repeatable trigger is useful evidence for the device, cable, hub, or a physical port; it is not a reason to keep reinstalling an otherwise stable controller driver.
If the controller still crashes after every software step
When the correct OEM driver, BIOS, controller firmware, and device-isolation tests do not stop the failures, the physical host controller may be unreliable. A compatible USB 3.0 PCIe expansion card can provide a replacement controller. Before buying one, verify the available PCIe slot, operating-system support, and the USB speed your devices require. Treat replacement as a last resort after the software and peripheral tests, not as the first response to a filename on a blue screen.
Quick Recap
When the fix is complete
- Run the computer with essential USB devices first and confirm that it survives several restarts and normal use.
- Reconnect remaining peripherals individually, recording any device, cable, hub, or port that reproduces the failure.
- Keep the OEM driver version, BIOS version, and the original stop-code notes so a future regression can be identified quickly.
- If a replacement controller is installed, verify that its card, slot, driver, and required USB generation match before moving all devices to it.
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