Is it possible to install a 64 bit OS on 32 bit PC?

Question

I asked this in Unix and there suggested to ask it here.

I was answering a question on a Linux Facebook group where somebody asked if it was possible to install a 32 bit OS on 64 bit PC. My answer was:

It is absolutely possible to install a 32 bit OS on 64 bit PC. But it is impossible to install a 64 bit OS on 32 bit PC.

Well, then somebody replied to my comment:

It is not impossible, but it is not correct to do it.

So... is it really possible to install a 64 bit OS on a 32 bit PC?

Solution 1

The answer is really, really simple.

Technically, a "32-bits" PC, as you call it, would be a PC whose CPU supports 32-bit computing but does not support 64-bit computing.

For example, a PC with an Intel CPU that supports IA-32 but does not support EM64T or IA-64 would be a "32 bits" PC. Indeed you would not be able to install a 64-bit OS on such a PC.

Solution 2

It isn't and will fail to get past to the installer - least from the small sample of OSes I've tried. These were done in virtualbox for ease of pretty screenshots.

I tried it with a few common 64 bit OSes - Windows 10 (I had build 1511 lying around)

Booting into an existing install throws a very similar failure, asking for a PAE enabled processor.

And Windows 7

Maybe its not just Windows.

Lets try a Ubuntu 16.04 livecd

Pretty sure for any pure 64 bit OS, you wouldn't get past the initial stages of install disk booting. While I didn't test it extensively switching a installed 64 bit system to a 32 bit host is also likely to end badly.

Solution 3

You can manage to install it (with some hacking), but it would be useless, because it would not boot. So you can technically, but I wouldn't recommend doing it, because most people like to have a computer that can boot.

If your computer came with a 32-bit OS, and the 64-bit OS runs fine, then you should check your actual computer, because sometimes 64-bit computers come with 32-bit OS's.

Comments

[LMiller7]

Precisely what do you mean by a 32 bit PC? The answer depends entirely on that. Bottom line is that the PC must be 64 bit capable, regardless what OS is currently installed. Many of these currently have a 32 bit OS installed.

[juankvillegas]

@LMiller7 I mean a 32-bit hardware.

[Mokubai]

You can install a 64-bit virtual machine guest on a machine that has a 32-bit host operating system. You still need a 64-bit processor and therefore a 64-bit capable machine.

[TheCrazyProgrammer]

No you can't. Hardware must be 64 bit capable to install a 64 bit OS.

[tvdo]

@Mokubai You could in theory install a 64-bit guest within a pure 32-bit CPU if you perform emulation (binary translation). Of course, doing so would be horribly inefficient and is not a typical virtual machine in the modern hardware-accelerated sense of the word.

[behrooz]

@Bob I don't think there are any 32-bit cpus out there that support any kind of virtualization.

[Daniel B]

@behrooz What Bob has described doesn’t rely on any hardware support. It’s purely in software. QEMU can do it. It can also emulate an ARM CPU on a x86 PC. It’s incredibly slow.

[satibel]

you can install a 32 bit os on a 8 bit micro processor, so you could run a 64 bit os on a 32 bit processor. see: dmitry.gr/… time to boot: 2 hours.

[behrooz]

@DanielB Yes, that was my point. I've been using qemu since 0.1

[Ramhound]

Considering all Intel/AMD 64-bit processors are x86 processors, and all x86 processors are 32-bit processors, what hacking would have to be done? The question is not clear enough to assume the author is talking about the very small subset of outdated unsupported x86 processors that do not support the AMD64 extension.

[misha256]

After re-reading your answer a couple of times I can see you are technically correct. You could install (i.e. get the files onto the hard drive) a 64-bit OS but, yeah, it would not even boot.

[Jamie Hanrahan]

True only for some definition of "install". The Windows installation procedure will reject the attempt to install the 64-bit product on a 32-bit platform. You won't even get a minute into the installation. Or, if you have one of the universal installers that asks "which one do you want to install", then on a 32-bit platform it simply won't ask the question; you won't have the chance to select the 64-bit version.

[Noah Cristino]

That's why I said if you manage to install it, because I'm sure it's possible somehow, since I have heard of people doing it and not being able to boot. @JamieHanrahan