If the system does not automatically prompt to upgrade Win8.1, how can I manually upgrade to Win8.1

If the system does not automatically prompt to upgrade Win8.1, how to manually upgrade to Win8.1 through ios image file?

Scenario

When you are officially buying genuine or have an ISO Mirror image file with Windows 8.1 and a 25-digit product key. This document will take you step by step through a CD (mirror) installation to upgrade to Windows 8.1. The disc image used can be obtained from a Microsoft MSDN subscription account or a TechNet subscription account or a third party website.

Note: Due to the upgrade installation of the system, computer settings, data changes or loss may occur. It is recommended that you do a backup of your personal data before the actual operation. Also make sure your computer has Windows 8.1 driver support. After upgrading to 8.1, you may need to reinstall common software and drivers.

The test hardware of this document is Lenovo IdeaPad Y400 notebook, hardware configuration is Intel I5 3210M, 4G memory, 1TB hard disk. The test ISO CD image file used is Microsoft MSDN subscription account download. All of the following test screens and test times are measured on this hardware platform and are for reference only.

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