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The Asus P8P67 Deluxe motherboard uses an UEFI firmware to boot the system. Compared to the well-known BIOS firmware it provides many new features like nicer GUI, faster boot time, but more importantly it support booting in UEFI mode from GPT disks. This last capability is becoming essential as many new drives with a capacity of 2.5TB and 3TB are now available (MBR disks capacity is limited to 2TB).
The UEFI firmware of the Asus motherboard allows starting the system using an UEFI boot sequence or a standard BIOS boot sequence. The BIOS capability is provided to boot legacy OS like Windows XP. Therefore the Asus UEFI firmware provides a new set of options to specify boot devices and priorities which is somewhat different from what you find in classic BIOS. In this document we will present the Asus boot options, how to partition a GPT disk, how to install Windows 7 X64 in UEFI mode, and how to boot in UEFI mode.
Note that the Asus implementation of the boot sequence is more flexible than many other implementations. With the Asus UEFI firmware the boot mode is automatically selected by the targeted boot file/device without user intervention. In contrast most of the other implementation will require the user to enter the BIOS and specify the boot mode for switching between legacy OS and “UEFI OS”.

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Specifying boot devices in BIOS mode

In the BIOS mode the boot devices are organized by type of devices (Hard Drives, CD/DVD, and Network). For each type it is possible to define a boot order. This is done in the Boot Menu of the UEFI setup program by clicking on the corresponding BBS (BIOS Boot Specification) priorities entry located at the bottom of the Boot Menu page (you may have to scroll down to find them).
For example if you click on the Hard Drive BBS Priorities you will enter a submenu that presents all the drives connected to the system. Here you can define the boot order for the Hard disks. For example you can specify an SDD as the first priority (Boot Option #1) and a HDD as the second priority (Boot Option #2). This implies that the system will first try to boot from the SSD and if this fail it will try to boot from the HDD.
The same prioritization procedure can be used for the CD/DVD as well as for the Network devices.
Note that the Network Devices BBS Priorities entry only shows up if you have enabled the LAN (Intel / Realtek) Oprom options.

Once you have defined the ordering for each type of devices you need to specify the overall priority. This is done in the Boot Option Priorities section of the Boot Menu. For example you can define to use the CD/DVDs first (Boot Option #1) and then to use the HDs after (Boot Option #2). Note that in the menu displayed you will only see the device with the highest priority for a specific type. For example if you have several HDs you will only see the highest priority one (the SDD in our previous example).

Using the above examples the boot manager would first try to boot from the CD/DVD. If this fails it would try to boot from the SDD and if this fails it would try to boot from the HDD.

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Specifying boot devices in UEFI mode

The way boot options works in UEFI differs from legacy BIOS. The UEFI boot option:

Therefore during initialization the Asus firmware looks for UEFI boot files on removable devices (maily CD/DVD or USB stick). If such devices are present and contain the appropriate efi file in the appropriate directory they appear in the Boot Option Priorities section. The name of the devices is prefixed with “UEFI:” string. For example if you have inserted a Windows X64 installation disk in your DVD drive you will now have two entries for the DVD drive and the second entry will be prefixed with UEFI: . Selecting the first one will boot the system in BIOS mode while selecting the second one will boot the system in UEFI mode.
You will probably also find special UEFI entries that are added by the OS during installation. This information is stored by the OS into NVRAM and is displayed by the Asus firmware. You will not find any description for them in in the Asus documentation as they depend on the software installed by the user. For example if you install Windows 7 X64 on a GPT disk then a “Windows Boot Manager” entry is proposed as an option but another OS could have added a “Ubuntu Boot Manager” entry.
All the entries prefixed by UEFI: can be prioritized in the Boot Option Priorities section of the Boot Menu. However this is not really useful as the first one should always be used.
Of course in UEFI mode the BBS specifications are totally ignored as the order of the boot sequence is now defined by the EFI boot manager. In the case of the Windows boot manager the order is defined in the BCD store. You can use the bcdedit utility to display or modify these special entries (e.g. bcdedit /enum firmware).

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Specifying boot devices in practice

If you do not use the UEFI boot capability then you should first define your boot drive in the HD BBS priorities section and then specify if you prefer to boot from the HD first or the CD/DVD first in the Boot Option Priority section.
If you need to boot from a GPT disk then you probably want to define the “Windows Boot Loader” as your first priority boot option and mostly ignore anything else.

The Boot Override section

This section of the Boot Menu allows booting from a specific device immediately. Therefore you should see an entry for all bootable devices including the UEFI boot devices.
This list contains the same entries as the menu list presented by pressing the F8 key during post.

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Windows UEFI boot sequence detail

Assuming you have installed Windows 7 X64 on a GPT disk, the following boot sequence happens:

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Where are the UEFI Boot information stored

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Creating GPT disk Partitions for Windows

The following procedure describes how to create a GPT disk and to create 3 Primary partitions. This would allow for example to install Windows 7 on the first and second one and to keep the third one for user data. In order to be used with Windows, a GPT disk must also contain two hidden partitions called the ESP (EFI System Partition) and the MSR (Microsoft reserved) and they must be placed in this order and before the primary partitions.
For partitioning the GPT disk we are going to use the Windows diskpart utility. This utility can work with any type of Disk (HDD & SDD) and handle correctly large disk above 2TB as well as disk using Advance Format (4K size blocks) or 512e Format (especially in term of alignment). The following operations can be done prior to the Windows installation or during the installation (as described below).
Be very careful when using the diskpart utility as it can remove all information on a disk and/or partition without warning or confirmation.
The utility needs to be started from a command shell with the administrator rights. Type diskpart to get the diskpart> prompt.

Note that if you want to create a GPT disk with only one Primary partition that occupy the complete disk you do not need to pre-partition the disk as the Windows installation will take care of this for you. In that case you can use the diskpart utility just to clean the disk and then convert it to GPT.

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Windows 7 X64 Installation on a GPT Disk

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UEFI / GPT Caveats

Open Questions

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Useful References

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