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Windows 7: Reinstall, had to disable UEFI. Driver warnings, yet everything works

12 Dec 2014   #1

Microsoft Windows 7 Ultimate 64-bit 7601 Multiprocessor Free Service Pack 1
Reinstall, had to disable UEFI. Driver warnings, yet everything works

Hi. Six months ago, I built this PC using a new SSD for the OS and two old HDDs for storage. ASUS mobo and Intel processor. The OS installation didn't cause any problems.

Due to constant BSODs last week, I decided to reinstall the OS. At the 'Where do you want to install Windows' screen I had this message against ALL THREE drives:

'Windows cannot be installed to this disk. The selected disk has an MBR partition table. On EFI systems, Windows can only be installed to GPT disks.

I entered BIOS and reset it to Default (assuming that would be its state six months ago). Same story, unfortunately. So I did some googling and managed the install by accessing BIOS/CSM/Boot Device Control and selecting 'Legacy OPROM only' (as opposed to UEFI & Legacy OPROM only).

After the install, I attended to my drivers differently than last time (where I went to the ASUS website). Instead, I installed Intel's 'Driver Update Utility' which only found one driver for me graphics. Given that I already had sound and internet connection, I was happy the mobo must have had the proper chipset and LAN drivers.

After all that, here's what I'd like to ask you:

If 'default' BIOS wouldn't let me reinstall, why did I have no problem the very first time?

I presume I'm not benefitting from UEFI? Should I be bothered?

In Device Manager/Other Devices, I have 3 yellow triangles: a) Ethernet Controller, b) PCI Simple Communications Controller and c) SM Bus Controller. Given that I have all the functionality I need I'm inclined to just ignore these warnings, what do you think?

Thanks for taking the time to read this and perhaps offer your thoughts.
My System SpecsSystem Spec
13 Dec 2014   #2
Microsoft MVP


Follow these steps for Clean Reinstall Windows 7 based on what's worked best in tens of thousands of installs we've directly helped with here, and which has been followed by over a million users without a single complaint or return with problems by those who stick with its steps.

As to UEFI, it's worth making some effort to benefit by it's improvements. So I'd start over and set to UEFI and Legacy, unplug all other drives besides SSD target drive, boot the Win7 DVD as a UEFI device, delete all partitions during the booted install to clear the formatting and try a UEFI install. If deleting isn't enough boot into the disk Command Line as shown in DISKPART At PC Startup to run Diskpart Clean Command.

Let us know if there are any problems. If in doubt about BIOS settings, camera snaps are a real help. Attach file using paper clip in reply box.
My System SpecsSystem Spec
13 Dec 2014   #3

Microsoft Windows 7 Ultimate 64-bit 7601 Multiprocessor Free Service Pack 1

Quote   Quote: Originally Posted by gregrocker View Post
boot the Win7 DVD as a UEFI device
Hi gregrocker and thanks for that. Is there more to the quote above than meets the eye? When I first inserted the DVD, BIOS would have been set to 'UEFI & Legacy' but I got the 'cannot install to this drive' message...
My System SpecsSystem Spec

13 Dec 2014   #4
Microsoft MVP


You had to boot the disk to get to the screen which gives you that error, right?

What I am asking you is if you are given UEFI boot options similar to these:

Notice that there are two DVD drive listings there, one being for a UEFI install and the other (without UEFI) being for a Legacy Install. I asked you if you booted the disk as a UEFI device.

If you don't have the UEFI DVD choice in Boot menu, what are the exact UEFI, CSM, Legacy BIOS settings choices in BIOS setup.

You can also try a UEFI flash stick formatted using Option One of UEFI Bootable USB Flash Drive - Create in Windows
to see if you get a UEFI flash stick listing in BIOS Boot Menu. The ISO to create this is provided in Clean Reinstall Windows 7 which are the steps to stick closely with if you want to get and keep a perfect install.
My System SpecsSystem Spec
13 Dec 2014   #5

Microsoft Windows 7 Ultimate 64-bit 7601 Multiprocessor Free Service Pack 1

I'm fairly sure that I didn't get a UEFI DVD option in the Boot priority list.

Right now, my PC is running fine so I'm loathe to start all over again. But many thanks for your time - I'll bookmark this for the next occasion where I need to reinstall.
My System SpecsSystem Spec
13 Dec 2014   #6
Microsoft MVP


Glad to hear it. As long as performance is good, then you're really not missing that much without the UEFI install. However at reinstall I'd give it a try with our help if necessary so you can compare the mobo features of a UEFI install to see if you're missing anything.

Enjoy Win7.
My System SpecsSystem Spec

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