Boot Windows 7/8 from GPT on BIOS system : No hybrid MBRs or DUET!

Robb please let us know how performance turns, especially boot times. This is valuable information that will help others who will find this thread in searches and our linking it to help them do an MBR install to GPT disks.

The reason I focused on boot time is that reports of Win7 being installed on flash drives have always that they are deadly slow due to the USB controller not being nearly as fast as HD. This may vary with USB3 now.

But having only the boot files on USB 3 is fascinating and it would be great to see a video of it booting.

Thanks guys.

I would say that the boot process has at the most about 10 seconds added to it. I am using an old sandisk USB 2.0 flash drive, so I don't think it's too bad. I will post a video of the boot process tomorrow.

Ahh had gotten busy...

@Robb20 : You're welcome. Follow the reboot.pro thread in the first post for further developments if you are interested :). And I'm surprised it adds TEN seconds to the boot time. At most the files involved would be about 10MB large, and that is peanuts even for USB 2.0.

@greg :
nitpick :

gregrocker said:

... do an MBR install to GPT disks.

do a BIOS install to GPT disks.

:)

Hello Milindsmart, thank you for your post. This is the only guide that I could find that suggested that this was possible with 32 bit windows 7.
I am attempting to upgrade my htpc hard drive from 250GB to 3TB, it had win7 32bit installed in an MBR partitioned drive. I tried to follow your guide but some of the steps couldn't be executed the way you described them, so I have doubts about the process. Could you look through my process and tell me if something is wrong?

1) clone 250gb disk to 3tb drive (clonezilla), test boot (worked, partition was/is ntfs)
2) boot with old disk and convert new disk to gpt non-destructively (AOMEI partition assistant lite)
3) resize 250gb partition on new disk to 100gb (now OS only) and create 2.7TB NTFS partition for recordings (AOMEI partitino assistant lite)
4) remove old drive, attempt to boot to cmd prompt with windows 7 32 DVD, get an error that its "System Recovery Option is not compatible with the version of windows you are trying to repair"
5) put old disk back in and boot it, run cmd and follow your instructions except bootsect is not a recognized command. Run bootsect from the win7 32 bit dvd under 'boot' folder. This step is targeting a USB flash drive.
6) reboot with old drive removed, usb flash drive is found, boot attempt (flash drive blinking light), and black screen only. no booting, and NO bios 'OS not found' message.

I attempted both fat32 and NTFS formats for the flash drive, but both exhibited the same black screen and didn't boot. Is there some way I can debug the boot process and figure out where it's going wrong? Is there something I need to add to the win7 32 bit install to allow it to boot from the GPT disk?

thank you for the help and tutorial. If this works it could help a lot of people in a similar situation.

Hey cuisinart,
Thanks, as far as I know this method is new, so this being the only one is expected.

cuisinart said:

4) remove old drive, attempt to boot to cmd prompt with windows 7 32 DVD, get an error that its "System Recovery Option is not compatible with the version of windows you are trying to repair"

There's a way around this : just press Shift + F10 at that point.

I'll certainly help you debug, it's not very hard either, but I suggest you redo the steps with only the new hard disk and USB stick connected. Windows installer doesn't handle multiple disks very well, gets confused.

cuisinart said:

I attempted both fat32 and NTFS formats for the flash drive, but both exhibited the same black screen and didn't boot.

All my experiments indicate that FAT32 does not work for the system volume (USB drive). Stick to NTFS.

Nice work. Bookmarked

Thanks, I saw that. A half day of work is about all I'm willing to spend on this, and a USB drive on a computer that just sits in the corner and runs 24-7 is fine.

Honestly, I'm surprised to see so many experts telling people they have to install windows x64 on fat32 to get gpt boot going. This is an ugly anachronism and shouldn't be the suggested solution.

Nobody tells anyone to install 64 bit to FAT32. When you format partitions for UEFI install it just happens to format the EFI partition as that, not the entire hard drive.

We offer Best Practices (many of which were developed here) that have made this the top tech forums in web history, serving millions of average consumers. We are not about to put any consumer through the hoops you've just jumped unless they specifically request it, especially for 32 bit which doesn't even address more than 3.5 gb RAM so would only be needed in the rarest cases, if then.

I admire the persistence and ingenuity in this thread but it is anomalous and may never be requested again. Meanwhile every day we help more consumers sort the UEFI firmware BIOS settings which is different on every model, doing the diligent support that the mobo and PC maker's don't begin to provide.

TBH I consider UEFI an unneeded layer that greatly complicates installation and Repair protocols that worked just fine before and now must be completely reworked differently for every mobo. As with RAID we only see problems with it here, and rarely see a single positive thing mentioned except from consumers.