# Install Win10 64bits to dual boot withWin7 32bits



## baldyeti (Jul 23, 2016)

Hello, i currently run Windows 7 from a C: primary partition.
I would like to install Windows 10 on my D: drive (defined in a logical/extended partition).

But i would like the drive letters to remain the same under both OS's (so under Win10, %windir% would be D:\Windows). Is this possible, specially given that the existing windows7 installation is 32 bits but i want to install windows10 64 bits.

Long ago i had such a dual-boot between XP and Win7 and running setup.exe from XP (rather than booting from DVD) achieved exactly what I described. The extra complication this time is the move from 32 to 64 bits so I suppose i will not be able to launch the 64-bits setup.exe from a system running win7 32 bits ?


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## flavallee (May 12, 2002)

If I understand you correctly:
The hard drive in your computer(no description given) is divided into C: and D: partitions(no capacities given).
Windows 7 32-bit(no version given) is currently installed in the C: partition.
You want to install Windows 10 64-bit in the D: partition.

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## baldyeti (Jul 23, 2016)

It's Win7 Pro, both partitions are 250GB in size with resp about 50GB and 100GB available (C,D).


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## DaveA (Nov 16, 1999)

Go here you the requirements of Windows 7
https://support.microsoft.com/en-us/help/10737/windows-7-system-requirements


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## Triple6 (Dec 26, 2002)

baldyeti said:


> But i would like the drive letters to remain the same under both OS's (so under Win10, %windir% would be D:\Windows). Is this possible, specially given that the existing windows7 installation is 32 bits but i want to install windows10 64 bits


Why is that a requirement?


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## baldyeti (Jul 23, 2016)

Triple6 said:


> Why is that a requirement?


Because i have quite a few open-source or portable apps that do not need the registry but may have C: all over their config files. Same for development projects. Or inter-linked excel files, etc...


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## Triple6 (Dec 26, 2002)

Oh so you don't want it to be D:\, this line threw me off:


baldyeti said:


> (so under Win10, %windir% would be D:\Windows)


Been a while since I installed dual boot Windows 7 but pretty sure by default it assigns C drive to the OS that boots, so both installations end up becoming C. This article seems to imply the same thing: (so under Win10, %windir% would be D:\Windows)

XP was different.


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## flavallee (May 12, 2002)

> It's Win7 Pro, both partitions are 250GB in size with resp about 50GB and 100GB available (C,D).


Please do the following in that computer so we can have more information on it:

Download and save the *TSG System Information Utility* (SysInfo.exe) to the desktop.
After it's been downloaded and saved, double-click it to run it.
Information about that computer will appear.
Return here to your thread, then copy-and-paste the ENTIRE text here.

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## flavallee (May 12, 2002)

If you set up that computer to dual boot with Windows 7 and Windows 10:

When you boot into Windows 7, it'll show the C: drive as Windows 7 and the D: drive as Windows 10.

When you boot into Windows 10, it'll show the C: drive as Windows 10 and the D: drive as Windows 7.

As Rob already said, the Windows version that you boot from will default to the C: drive.

Note: This is assuming the disc drive is assigned letter E: or later.

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## baldyeti (Jul 23, 2016)

flavallee said:


> When you boot into Windows 7, it'll show the C: drive as Windows 7 and the D: drive as Windows 10.
> 
> When you boot into Windows 10, it'll show the C: drive as Windows 10 and the D: drive as Windows 7.


That is exactly what I 'd like to avoid. What you describe is what happened with previous versions of windows, too, *provided* you install from DVD (or USB these days I imagine). It used to be that if you launched the setup.exe of the 2d version of windows you wanted to install from your computer running the original windows, and pointed it to install to D: (or any non-C; of course), D: would be the system drive of the 2d windows, even when booting it as running OS - no drive letter swap would occur, which is what I am after. I have not attempted this in the particular case of windows10 yet, plus the upgrade to 64bits complicates things i am afraid (setup.exe for win10 64 bits is a 64-bits executable i do no think i'd be able to launch from a computer running 32bits win7)


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## baldyeti (Jul 23, 2016)

flavallee said:


> Return here to your thread, then copy-and-paste the ENTIRE sysinfo output.


Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Professional, Service Pack 1, 32 bit
Processor: Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz, x64 Family 6 Model 23 Stepping 10
Processor Count: 4
RAM: 3068 Mb
Graphics Card: NVIDIA GeForce 210, 512 Mb
Hard Drives: C: Total - 239999 MB, Free - 48860 MB; D: Total - 255999 MB, Free - 77936 MB; E: Total - 255999 MB, Free - 75006 MB; M: Total - 255999 MB, Free - 32211 MB; T: Total - 390306 MB, Free - 172886 MB;
Motherboard: Intel Corporation, DG43GT
Antivirus: AVG AntiVirus Free Edition, Updated and Enabled


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## Triple6 (Dec 26, 2002)

I thought you wanted both Windows installations to be C drive, that's what Frank posted.

You need to boot from the Windows installation media, DVD or USB, not run it from from within the other Windows.


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## baldyeti (Jul 23, 2016)

Triple6 said:


> I thought you wanted both Windows installations to be C drive, that's what Frank posted.
> 
> You need to boot from the Windows installation media, DVD or USB, not run it from from within the other Windows.


Sorry I do not think so, booting from DVD will make the installed OS always see its system drive as C: 
I want the C drive associated with the primary partition and the D drive associated to the logical partition under both OS's.


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## Triple6 (Dec 26, 2002)

So you want the partition with Windows 7 to always be C and the partition with Windows 10 t always be D drive regardless of which one is booted up?


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## flavallee (May 12, 2002)

> Hard Drives: C: Total - 239999 MB, Free - 48860 MB; D: Total - 255999 MB, Free - 77936 MB; E: Total - 255999 MB, Free - 75006 MB; M: Total - 255999 MB, Free - 32211 MB; T: Total - 390306 MB, Free - 172886 MB


According to your SysInfo.exe log, it's showing *5* partitions - C: and D: and E: and M: and T:.
How many internal and external hard drives(not partitions) do you have connected to that computer, and what are their capacities?

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## baldyeti (Jul 23, 2016)

There is a single 2TB HD. Only C: corresponds to a primary partition, the other logical units are defined within one extended partition (MBR-scheme, not EFI).


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## baldyeti (Jul 23, 2016)

Triple6 said:


> So you want the partition with Windows 7 to always be C and the partition with Windows 10 t always be D drive regardless of which one is booted up?


yes, exactly.


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## managed (May 24, 2003)

It might be easier to have the portable apps on a different partition than both 7 and 10, then you could have both Os's showing as on the C drive when they are running, which can be better. Is that an option you would consider ?
If it is simply installing 10 by booting from DVD/Usb stick will set it up like that. To install 10 without upgrading from an earlier version of windows _and get it activated properly_ see here :- http://www.thewindowsclub.com/directly-clean-install-windows-10-without-upgrading

EDIT : it doesn't matter if 7 is 32 bit and 10 is 64 bit.


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## baldyeti (Jul 23, 2016)

managed said:


> It might be easier to have the portable apps on a different partition than both 7 and 10, then you could have both Os's showing as on the C drive when they are running, which can be better. Is that an option you would consider ?


I'd rather not ;-) which is why i started this thread


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## managed (May 24, 2003)

Yes I just skimmed through this thread and I see why you want D to be same partition within both 7 & 10.
I suggest you try starting the 10 install from within 7 and see if that works, if 10 gets C you can always remove it.


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## baldyeti (Jul 23, 2016)

managed said:


> I suggest you try starting the 10 install from within 7 and see if that works


I cannot do that as hinted in the original post: the x64 setup.exe won't run under x32 (I have now tried and can confirm)


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## managed (May 24, 2003)

The thing is you're trying to do the opposite to what most people want so there's not much info about this around.

I _think_ if you install 10 onto any partition other than D you could then have the 2nd partition as D by changing it's drive letter, if necessary, in 10's Disk Management (DM). This way you could start the install by booting a DVD/Usb stick and 10 would be on C when booted into but the 2nd partition would still be D. Other than that, because you can't start the 10 64 bit install from with 32 bit 7, I can't see any way to install 10 onto the 2nd partition _and_ it also having the D drive letter within 10 itself.

Drive letters change, it's better to either use the partitions position on the drive (I said 2nd partition above assuming what you refer to as D is in fact the 2nd one, it may not be) or rename the partitions to something like Windows 7, Windows 10, Data, ... in Windows/File explorer.

You can see the partition positions in DM.

Micro$oft (M$) start numbering drives from 0 but partitions from 1, also the Boot partition in DM actually holds the bulk of Windows and the System partition the boot up files, the exact opposite of what you might expect and also the opposite of what everyone else names them. If you want to know why ask M$, I have no idea !

EDIT : A screen-shot of DM would help us to talk about the partitions more easily.


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## Triple6 (Dec 26, 2002)

Do you really need these programs/directories to be used from both operating systems? Could they be edited once so they reside on another/third partition that is then never affected by O/S installations?

What about placing these programs/files on another partition and creating symbolic links for a directory in the C drive? http://www.howtogeek.com/howto/16226/complete-guide-to-symbolic-links-symlinks-on-windows-or-linux/


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## baldyeti (Jul 23, 2016)

managed said:


> The thing is you're trying to do the opposite to what most people want so there's not much info about this around.


Indeed i had not been able to find anything before asking here. I was hoping there might be an advanced or hidden installation option I had not found. The capability must exist as it is actually possible to end up with a non-C %HOMEDRIVE% when launching the setup from a running OS. Perhaps this is exposed for unattended installations (which i have never used myself) ?

Thanks anyway all for the valuable suggestions. I am in no hurry and am currently thinking of freeing some space to create a new logical unit. I'd then use that as my system drive for a Win10 clean install. For anything but the original C: i should be able to correct drive letters if needed through the "disk management" applet. Then a couple (symbolic) links from folders on the original C: drive to the new one should make the change mostly transparent.


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