Fix STOP Error 0x000000A5 when Installing Windows 7

Some users are complaining about the fact that they end up seeing the Stop Error 0x000000A5 every time they attempt to install Windows 7 on their computer. In most reported cases, the error appears during the phrase where the installation is ‘Copying Windows Files‘.

STOP Error “0x000000A5” Error upon installation of Windows 7

In most cases, this particular issue is caused by a BIOS inconsistency. In order to fix the issue, in this case, you’ll need to follow the documentation provided by your motherboard manufacturer in order to update your BIOS version to the latest version.

In case you’re using a traditional HDD but your BIOS is configured to use WIMBoot, you will need to adjust some BIOS settings in order to allow the installation in Windows 7. In this case, go into your BIOS settings and adjusting the LPSS & SCC configuration in order to accommodate Windows 7.

However, as it’s been reported by some affected users, the Stop Error 0x000000A5 can also occur due to a failing RAM or by a partially broken RAM slot (or a slot filled with dust and lint). In this case, you should be able to fix the issue by replacing your RAM stick or by changing the RAM slot that you’re actively using.

On an older rig, you might need to force the installation of the Standard PC HAL if the BIOS that you’re using is not fully ACPI compliant. This can be done during the first screens of the Windows installation sequence.

If all else fails, you should reset your BIOS or UEFI settings to the default and redo the installation again to see if the issue is still occurring.

Updating your BIOS to the latest version

As it turns out, in the vast majority of cases, this particular issue will be caused by a BIOS inconsistency. This stop code usually indicates that the BIOS version is incompatible with the Advanced Configuration and with the Power Interface (ACPI) that is supported with Windows 7.

If this scenario is applicable, you should be able to fix the issue by updating the BIOS version to the latest available. But keep in mind that due to the fact that BIOS interfaces are vastly different across various motherboard manufacturers, it’s not possible to provide you with step-by-step guides.

The best way to get specific instructions on updating your BIOS version is to go online and do a search query on ‘BIOS Update + motherboard model‘ and read the documentation on the official website very carefully.

Keep in mind that most motherboard manufacturers will offer their own BIOS updating utility, so following the steps to the letter is essential. Asus has E-Z Flash, MSI has MFlash, etc.

Updating your bios version

Here’s a shortlist of official documentation directories for BIOS updating for some of the most popular motherboard manufacturers:

If you’re looking for some general guidelines that will allow you to update your BIOS version, follow the instructions below to do it via a USB flash drive:

Note: Make sure to consult the official documentation for step by step instructions. This is just a general guideline.

  1. Start by ensuring that you have a blank USB flash drive sat the ready. If it’s already filled with data, back it up and then right-click on the flash drive and choose Format from the context menu.
    Formatting the USB drive
  2. Inside the Format screen, set the file system to FAT32 and check the box next to Quick Format. Next, click on Start to format the drive.
    Formatting the removable drive 
  3. Once the operation is complete, visit your motherboard manufacturer’s website, consult the BIOS update documentation and download the latest BIOS firmware version. Next, copy that file to the USB flash drive that you’ve just formatted.
    Downloading the latest BIOS version

    Note: Depending on your motherboard manufacturer, you might need to make some additional changes to the files used for the BIOS update – that’s why it’s very important to consult the official documentation.

  4. After you manage to copy the Boot files on the USB flash drive, restart your computer and press the required (Setup key) at the next startup to access your BIOS settings menu.
    press a key to enter setup or bios
    Press [key] to enter setup
    Note: If the Setup screen doesn’t appear on the screen, try pressing the Esc, Del, or the F keys (F2, F4, F6, F8, and F12). In case none of these potential BIOS keys work, search online for the specific BIOS Settings key according to your motherboard model.
  5. Once you’re inside your BIOS settings, look under the Advance settings for an option named Update System BIOS (or similar)

    Updating the System BIOS via USB flash
  6. After the update operation is complete, restart your computer and wait for the next startup to complete. Once you reach this point, you can safely remove the USB flash disk from your computer.

If you’ve already taken some steps to update your BIOS to the latest version and you’re still encountering the same error message, move down to the next potential fix below.

Adjusting the LPSS & SCC Configuration

If you’re using an older motherboard and a traditional HDD, it’s possible that you’re struggling with the Stop Error 0x000000A5 due to inconsistency with WIMBoot. Keep in mind that WIMBoot is not supported on traditional drives that still use rotational components or hybrid drives (that contain both solid-state and rotational drive components)

If this scenario is applicable, you should be able to fix the issue by accessing your BIOS settings and adjusting the LPSS & SCC Configuration so that it’s configured to work on Windows 7. Several affected users have confirmed that this operation finally allowed them to complete the installation of Windows 7 without encountering the Stop Error 0x000000A5.

Here’s a quick guide on adjusting the LPSS & SCC Configuration from the Advanced BIOS settings menu:

  1. Open up the machine that you’re encountering issues with and start pressing the Setup key as soon as you get to the initial screen.
    Pressing the Setup key to enter BIOS settings

    Note: The Setup (BIOS) key should be installed on the screen. If you’re having trouble finding your particular Setup key, search online for specific instructions on accessing your BIOS or UEFI settings.

  2. Once you’re inside your BIOS settings menu, go to the Advanced settings menu and look access the entry named LPSS & SCC Configuration.
    Accessing the LPSS & SCC Configuration menu
  3. Inside the LPSS & SCC Configuration menu, change the drop-down menu associated with Operating System to 7.
  4. Save the changes that you just made your BIOS settings, then attempt to repeat the installation of Windows 7 and see if you’re able to complete it without encountering the same Stop Error 0x000000A5.

Replacing the RAM or using a different slot

As it turns out, the Stop Error 0x000000A5 can also occur if the memory is not properly seated or if the RAM stick that you’re using is starting to fail. This is only applicable if you’re encountering this issue during random intervals or at the system startup.

Some affected users that were dealing with the same kind of issue have reported that they did a memory test to see if there are any issues with their RAM.

If you’re currently overclocking your RAM frequency & voltage, revert to the default values and monitor the usage with a program like HWmonitor to check for any voltage or temperature spikes that might end up producing this error.

Additionally, you can also run the Memtest utility to verify the integrity of your RAM files.

In case you find no red flags with your RAM, simply change the RAM slot that you’re currently using. If the issue doesn’t repeat once you change slots, there’s a high chance that you’re dealing with a faulty RAM slot on your motherboard – in this case, take your computer to a technician for further investigations.

Installing the Standard PC Hardware abstraction layer (HAL)

If you’re using an older rig, it’s also possible that you’re encountering the Stop Error 0x000000A5 due to the fact that the BIOS you’re trying to use during the installation of the new Windows version.

In case this scenario is applicable, you should be able to fix the issue by obtaining a BIOS that is fully ACPI compliant. By doing this, Windows will automatically disable the installation of the ACPI HAL and install the Standard PC HAL.

Here’s a quick guide on installing the Standard PC Hardware abstraction layer:

  1. Reboot your machine in order to bring back the Windows Setup screen.
  2. once you see the ‘Press F6 if you need to install a third-party SCSI or RAID driver‘ bottom prompt, press F7 (Not F6) in order to bypass the installation of ACPI and install the Standard PC HAL.
    Installing the Standard PC HAL
  3. Follow the installation prompts normally – This time, you should no longer be interrupted by the same Stop Error 0x000000A5 error.

Reverting BIOS / UEFI to the Default Settings

If none of the methods above have worked for you and you’ve previously made sure that you’re using the latest BIOS / UEFI version and that Standard PC HAL is active, one last fix that might fix the issue for you is to revert every BIOS or UEFI settings to the default values.

Keep in mind that due to the fragmented nature of BIOS versions and the fact that newer rigs use UEFI instead, we can’t provide you with a definitive guide that will allow you to revert the values of BIOS or UEFI to the default.

Because of this, we created two separate guides that will allow you to do this regardless of the boot technology that you use (BIOS or UEFI). Follow whichever guide is applicable to your current situation.

Resetting BIOS Settings to Default

  1. Power up your machine (or restart it) and start pressing the Setup (Boot key) once you get to the original screen.
    Pressing the setup key

    Note: If the boot key is not displayed on the screen, try Esc, Del, F1, F2, F4, F8, F12 or search online for the dedicated setup key.

  2. Once you’re inside your BIOS settings, look for an option named Setup Defaults (or Setup Default, Factory Default or Reset to Default), confirm, then save the changes to return to the default BIOS configuration.
    Load default system configuration

    Note: If you have the generic BIOS version that most manufacturers are using you can revert back to the default settings by pressing F9 once you’re inside the BIOS setting menu.

  3. Once you’ve ensured that the changes are saved, exit the BIOS settings and attempt to perform the Windows 7 installation again and see if the issue is still occurring.

Resetting UEFI Settings to Default

  1. Press Windows key + R to open up a Run dialog box. Next, type ‘ms-settings:recovery’ and press Enter to open up the Recovery menu of the Settings app.
    Accessing the Recovery tab
  2. Once you land inside the Recovery window, click on the Restart button associated with Advanced startup.
    Accessing Advanced Startup using Settings
  3. After you do this, your computer will restart directly into the Advanced Options menu. Once you get to this point, navigate to Troubleshoot > Advanced Options and click on UEFI / BIOS Firmware settings.
    Accessing the UEFI firmware settings
  4. From inside the UEFI settings, click on the Settings menu and search for the option named Restore Defaults (or similar).
    Restore UEFI settings to the defaults
  5. Next, complete the operation and save the changes before you exit the UEFI settings.
  6. At the next system startup, attempt to install Windows 7 again and see if you are able to complete the process without encountering the Error 0x000000A5 error.
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Kevin Arrows


Kevin is a dynamic and self-motivated information technology professional, with a Thorough knowledge of all facets pertaining to network infrastructure design, implementation and administration. Superior record of delivering simultaneous large-scale mission critical projects on time and under budget.

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Fix STOP Error 0x000000A5 when Installing Windows 7

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