How to change Windows 10 upgrade from 32-bit to 64-bit?

would be very nice to have.

"...and try this on a new blank HDD. I'd keep the old HDD for a fall back position".

Thanks. I shall follow this advice.

Basically you install x64 win10 on a separate partition/Hdd. but a copy of the upgrade OS must be on the computer because win10 has to be able to find the activation KEY of that (also be sure you know the key as well). The point here is..after it found the key and know it's a 32bits OS, will it still let you upgrade.

Once you've installed the 32 bit version of Windows 10, MS has saved info on it's registration server(s) that this PC is registered for 10. After that registration keys are no longer used. This is a change MS made with Windows 10. So as Bob says, you can create a new partition and install the 64 bit version with no problem. I've done this many times.
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Good luck.

It WILL ask you you for the key...or where to search for it. So it will be win10 key, which you don't have...or the upgrade OS which win10 has to find or it will not go on. When you do a normal upgrade (not clean install), it can verify this is a legit upgrade on the old system.

It's worked many times for me.

eventually comes back and asked for the key. That's what I have encounter. But I suppose no harm in trying. I may try again when I find a suitable computer and load a x32 OS on it. Something else I have ran into that's strange. I have a OEM win7 disc that has SKIP but I also have a retail win8.1 that don't have that..go figure.

To trip up the Microsoft Windows installer. Lesson learned so I use the Windows install to create those things.

I'm not clear about what you attempted to convey by "To trip up the Microsoft Windows installer. Lesson learned so I use the Windows install to create those things".

So, I refer to my last post "Clean Install on 2nd HDD went smooth---didn't get desired result".

I thought of making a clean install of Windows 8.1 x64 using my OEM DVD and then upgrade it to Windows 10 x64 using Windows Update.

Question is: Do I do it on 2nd HDD SATA 148 GB Seagate (2007) or by creating a partition on 1st HDD SATA 930 GB Western Digital (2013)?

Here it might be relevant to add that 32-bit Windows 10 is currently installed on 1st HDD. If I create a partition, it will also house 64-bit Windows 10 on a separate partition of 1st HDD.

As for 2nd HDD, it has now the non-functioning 32-bit Windows 10 which will get wiped out and get replaced by 64-bit Windows 8.1 followed by 64-bit Windows 10 upgrade.

By partitioning the 1st HDD 50-50, it will have a separate 465 GB compartment for 64-bit Windows 10 via 64-bit Windows 8.1 route.

In comparison to that, 2nd HDD will have 148 GB space for 64-bit Windows 10 via 64-bit Windows 8.1 route.

In his post "MS knows the PC is registered for Win 10 already" wpgwpg mentions "you can create a new partition and install the 64 bit version with no problem. I've done this many times". However, he did not mention if he upgraded via Windows Update or download on USB.

That leads to another question: If I should use the partition on 1st HDD instead of using the 2nd HDD, then should I adopt 64-bit Windows 10 via 64-bit Windows 8.1 route, or clean install with USB drive which I used for installation on 2nd HDD but system booted on all three occasions from 1st HDD? Details in my post "Clean Install on 2nd HDD went smooth---didn't get desired result".

In a few cases I used the release version ISO that I downloaded via this link:
http://www.microsoft.com/en-us/software-download/windows10 . However since I'm in the Insider program, I've often made an ISO from one of the insider builds and used that. In both cases once having installed the first version of Windows 10, I've always done clean installs in the 2nd partition. A 3rd thing I've done is set up a Windows 7 PC with dual boot to 7 and 8.1, then used the upgrade with the release version ISO on the 8.1 partition, resulting in 7 and 10 in a dual boot configuration. In this last case Windows 7 was the OEM version that came with the computer, and 8.1 was purchased. All of the above were done on 5 and 6 year old desktops.
So as you can see, there are numerous ways to do this.
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Good luck.

otherwise why only 1GB. use on that drive. Well...maybe practice makes perfect.

As for the comment on clean install, it was clean install, indeed, but obviously not a proper install as my own checks established that, but now I realize that I shouldn't have shared my experience at this forum, in detail. For, people seem to interpret things differently.

As for your question of 1GB, what I had stated was: on 2nd reboot space occupied grew only by 1 GB...on 3rd reboot space grew to 13 GB. It was a phenomenon not witnessed by me earlier through numerous clean installs during which I learned a lot from trial and error but none of them were remotely related to Windows 10 installations. Now, what commentator made out of it was not within my power.

As for the saying "practice makes a man perfect", I had done clean install successfully during 1st week of Aug, and that clean install was done in 1st attempt, using USB drive which many people had reported to have failed.

But I reverted to Win 7 because licensed version of Avast Internet Security system made my (Win 10) PC very slow, including frequent hangs. Uninstall and reinstall Avast, more than once, did not help.

Graham Cluley advised his audience to better stay away from early installation of Windows 10. His advice was, let people report bugs, let Microsoft fix them, and then you install a better piece of software.

So, this time, I upgraded from Windows 7 to 10 using a different route (Windows Updates). It succeeded in first attempt this time again.

I guess, I should now close this topic. Enough has been discussed.

I had taken the following action based on R. Profitt's "I haven't read a solid answer on this beyond" after writing the post "Thank you" but before reading all answers up to Oldartq's "Ok, lets "skip" all I have said before"--

Win 10 32-bit (my opening post) had been upgraded from existing Win 7 Home 32-bit using Windows Update and the process was smooth and had succeeded in first attempt.

On 2nd hard disk of the same computer---blank, wiped using CCleaner Drive Wiper entire drive 1 pass, formatted, new volume created, drive letter assigned---made a clean install for Win 10 using USB drive---downloaded shortly after July 29 release.

Clicked the skip button, when asked, and the installation began smoothly, and ended without a hiccup. When the system booted, I opted for boot from the 2nd hard disk, where the new installation had recently been made.

However, system booted from 1st hard disk where 32-bit version had been upgraded earlier. Twice more, I attempted reboot, ensuring I asked for boot from the 2nd hard disk but, every time, system booted only from 1st hard disk.

Noticed that space occupied on 2nd hard disk was very small, contained PerfLogs, only one folder for Program Files, only one folder for users (Public), Windows, and Windows.old (empty).

On 2nd reboot attempt from the 2nd drive, space occupied grew only by 1 GB. On 3rd reboot attempt, space occupied grew by a couple of GBs---finally 13 GB---contained a 2nd folder for Program Files, but no 2nd folder for users (my folder).

For reasons not quite understood by me, folder additions and increase in occupied space took place one by one in each successive reboot attempt from new clean installation, a phenomenon which I had not witnessed any time during any of my prior installations on 3 PCs, mostly clean installs of Windows XP Pro, Vista, Win 7, and Win 8.1, all OEM versions, all 32-bit, except 8.1 64-bit.

Now, I am thinking of a clean install of Win 8.1 x64 on 2nd hard disk, and then an upgrade to Win 10 via Windows Update, and see what happens.

Any more thoughts would be welcome!

For the OS, around 10GB is about right. But grew from 1-13GB sounds weird. Got no idea what happen there.

Are you able to get the key on win10? I use "Belarc Advisor" to get computer information. You might be able to do a clean win10 x64 install and activate it with that key without using win8.1. or the original Hdd. Try that just for the fun of it.

Thanks.

Grew not "from" but "by" 1 GB...finally up to 13 GB.

However, the way it happened reboot 1 to reboot 2 to reboot 3 was weird, I had felt.

On couple of occasion---over past 30 years of PC use---I have witnessed several oddities where systems behaved in weird manner, beyond logic. Sometimes, I share them not to convey that software or hardware is bad but to hint at such possibilities; be prepared for such funny things to happen once in a while; no need to get confused, simply keep trying but systematically, and wherever possible, by taking a slightly different route.

I have a genuine Windows 8.1 DVD which I had used earlier for clean installation. It has a Certificate of Authenticity and the Product Key inscribed on it.

I intend to use it again to make a Clean Install and then Upgrade to Windows 10 via Windows Updates route as that I found simpler, dependable, and convenient than using Windows 10 downloaded on a USB drive---a few days after its release to public---when Windows 10 was ridden with bugs.

This USB drive was used by me this time while attempting a clean install on a blank internal HDD, which this time failed; though it had succeeded earlier but finally I had to replace that installation by Windows7 for reasons explained earlier.

My only question was: whether I should use a partition on main drive which would give 465 GB space or the blank disk which can offer only 148 GB space?

I should have avoided other details because it unnecessarily expanded the conversation beyond need while the real question was lost in the crowd. It was my mistake and I shall try to refrain from sharing non-essential details in future.

Now that I haven't got the answer to my real question, I am going to take a suo motu decision based on one of the respondent's experience: make a partition of main drive and clean install either by fresh download from Windows site on a USB drive or by first installing 8.1 and then upgrading to 10. I guess, I would take the first option first because it's less time consuming. I hope fresh download will be of better quality because Microsoft would have ironed out many a bugs during past seven weeks.

Thanks to all those who participated in the discussion, and particularly those who gave simple and useful suggestions for implementation.

you said "I have a genuine Windows 8.1 DVD which I had used earlier for clean installation. It has a Certificate of Authenticity and the Product Key inscribed on it."

If it is currently installed on another computer then you cannot use it. If it was used to justified an upgrade, you cannot use it. If it says anything about not for resale for use only on a new system, then you cannot use it.

With all the extra commentary you gave in your post, it is confusing as to what your real question is.

If you were to use the 1TB drive, because it has all the stuffs on it, it will be very time consuming to create another partition (resize then partition) and hopefully nothing go wrong in the process. Did you get the win10 key? If you did, that's key I believe MS associate win10 and that computer. Write it down..you might need it again some other time.

Instead of upgrade to win 8.1, just install win10 x64 alone now that you have the key. Give that a try and see how it go.

Closing thread.