Why UEFI, BIOS deny to install Windows?

Why UEFI, BIOS deny to install Windows?

Many PC users face the problem of Windows installation. When trying to install the operating system, the window “Installing Windows on this disk is impossible” appears. What is the problem? And how to solve it?

In this article we will look at some of the easiest ways to fix this error and break it down into shelves, but for this you need to understand what UEFI, Legacy, MBR and GPT are. After reading this article it will be clear why this error occurred and how to fix it. We will try to explain everything in a language accessible to novice users.

What happens after you press the power button on the system unit?

You probably know that when you press the power button, the hardware is initialized, all the hardware is diagnosed and then the operating system starts booting, which is what UEFI or Legacy BIOS is responsible for. You may have guessed by now that these are two different standards, but they perform the same function.

BIOS and its features

Why UEFI, BIOS deny to install Windows?

Let’s start with the oldest but still in use BIOS firmware, which is the firmware we run when we start the computer. You can access its interface with the delete or F2 key. In it we can see which computer components we have installed or change the boot parameters, the control is done only with the keyboard. In this entry I will tell you how this loader works and why we created the new standard.

This loader is sewn into the chip that is soldered on the motherboard and provides a layer between our computer hardware and the operating system. As I said a bit earlier, this firmware first checks all the connected hardware and only then runs the operating system. All this is done one by one, one by one. And this firmware uses the main MBR boot record, which supports hard disks up to 2 Tb and maximum 4 logical partitions.

UEFI and its features

Why UEFI, BIOS deny to install Windows?

Such principle of work as in BIOS began to be actively displaced since 2010. Intel developed its new firmware called EFI, later renamed UEFI, a more advanced program with an intuitive graphical interface, keyboard and mouse support. And each motherboard manufacturer has its own UEFI interface.

Why UEFI, BIOS deny to install Windows?

Unlike BIOS, which is similar to DOS, UEFI interface and functionality is closer to operating systems, which allows to initialize devices in multithreading mode, here is already used partition table GPT, which supports 128 logical partitions up to 8 exabytes. Security was also given attention here. We can install on your PC only registered operating systems. As you have already understood UEFI is superior to bios but still we can still use two modes of both uefi and bios on many PCs.

How can I fix the error “Installing Windows on this disk is impossible”?

Here we have a smooth approach to the error that occurs when installing the system. Most likely, you already had some system installed before and now you are trying to install a system with a different partition scheme.

As you have understood, different firmware uses different partition tables. In BIOS it is MBR and in UEFI it is GPT. So during the installation, the system warns us that the disk already has an MBR partition table, and we are most likely trying to install a system that is written with a GPT partition table.

There are two ways to solve this problem:

  • The first is to format the disk completely and create new partitions again, thus we will lose all information on your computer;
  • Or a second – you need write a bootable flash drive through the free Rufus program by selecting the necessary partition diagram, the installation should go without any problems.

Why UEFI, BIOS deny to install Windows?

Which firmware (loader) to choose from the beginning? It doesn’t matter. On our working PCs we didn’t notice much speed gain when using UEFI. But on a server it is certainly better to use UEFI with GPT instead BIOS.


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