Your PC’s CPU isn’t compatible with Windows 8 – Error Explained

Some people who are trying to install Windows 8 Release Preview are reporting an error. This error has been reported even by those who could run Windows 8 Consumer Preview on the same machine. While installing Windows 8 Release Preview , you may see the following error message:

This PC can’t run Windows 8

Your PC’s CPU isn’t compatible with Windows 8

PCNotsupprtWin8z Your PCs CPU isnt compatible with Windows 8   Error Explained

So what has changed since the Consumer Preview? Let us check what this error is and what Microsoft is saying about it.

As we can see, this error is related to CPU requirements for Windows 8 Release Preview. So to install Windows 8 RP, your CPU (processor) must support these features – PAE/NX/SSE2 .

Let us see what these means.

No-eXecute (NX) is a processor feature that allows marking of memory pages as non-executable. The feature allows the CPU to help guard the system from attacks by malicious software. When the NX feature is enabled on a system, it prevents malicious software code from being placed in accessible regions of memory to be executed when control reaches that memory location. Windows 8 requires that systems must have processors that support NX, and NX must be turned on”

“Streaming SIMD Extensions 2 (SSE2) is a previous standard that is supported in Intel and AMD processors. All processors that support NX also support SSE2.”

“To use the NX processor feature, the processor must be running in Physical Address Extension (PAE) mode. PAE is a processor feature that enables x86 processors to access more than 4 GB of physical memory on capable versions of Windows. “

The processor requirement won’t impact customers on modern systems, or on systems that meet logo requirements for Windows 7 because these systems have PAE-capable 32-bit processors that support NX and allow NX to be turned on. Only a small set of customers who have Windows 7 running on very old 32-bit processors without PAE/NX support will be impacted.

Check if your system  Supports NX or SSE2

To check this, there’s a Windows Sysinternals tool Coreinfo , a command-line utility. You can get it from here. Running this from the command line, will provide the required info –

coreinfoCPU Your PCs CPU isnt compatible with Windows 8   Error Explained

A supported processor feature will have the * character displayed next to the feature name, and a - character if not supported.

“If PAE is displayed as not supported in Coreinfo output, your system has a processor that is not PAE-capable, and cannot support NX. If PAE is shown as supported, but NX is displayed as not supported in Coreinfo output:

· Consult the feature set published by the CPU manufacturer to determine if NX is supported by the processor on your system.

· If the processor on your system does have the NX support, then your system may have misconfigured BIOS setting for NX support option.

If NX is supported on your system, can be turned on from BIOS settings if its not turned On.”

So check the BIOS and enable NX (“No eXecute bit”) or the equivalent XD (“eXecute Disabled”) feature in the BIOS settings. Look them in Advanced or Security options in BIOS. They may be referred by various names according to BIOS manf. They can be named No Execute Memory Protect, Execute Disabled Memory Protection, EDB (Execute Disabled Bit) , EVP (Enhanced Virus Protection) or by some oth name. So check for these.

If the BIOS doesnt show any of these option for NX , then check with BIOS manf for any BIOS updates which might have added this. Very old processors may not include this feature.

Error 0x0000260

A related error is also seen in when trying to install Windows 8 in a VM with an error 0x0000260.

“If the Virtual Machine (VM) is hosted on a system that supports NX, you must enable PAE/NX in the virtualization product’s settings or configuration manager when setting up the Windows 8 virtual environment. “

For more detailed info on PAE/NX/SSE2 requirement for Windows 8, Microsoft has published a Whitepaper -  PAE/NX/SSE2 Support Requirement Guide for Windows 8

This document details the processor support for the PAE/NX/SSE2 requirement in Windows 8, error cases and scenarios that customers encounter when machines fail to meet the requirement, and what to do to install Windows 8 on their PCs. The information provided in the document applies to Windows 8 and Windows Server 2012.

Microsoft’s Bill Fill explained in detail about this error in The Answers Forum. He starts with apology for the inconvenience caused by this issue and thanks the users for trying out the Release Preview. Further he says that Microsoft may contact a few of those who reported this issue if further info is needed as it may be a bug and has to be corrected before RTM.

Then he describes what exactly has changed since CP as users who could run the CP on their machine encountered this issue while installing RP on the same machine.

What has changed in Windows 8 RP, since CP

We did make changes in the upgrade detection logic since the CP. The changes revolve around the default installer and how it checks for precise CPU features before continuing. Windows 8 requires the NX capabilities of modern CPUs. This is done for security reasons to ensure that malware defense features work reliably. This is important as we want to ensure that people can feel safe using lots of different software including desktop apps and apps from the Windows Store. This means some very old CPUs will not work with Windows 8. In the CP we did not block the installer for the NX feature. Based on CP telemetry we felt adding the block to setup was warranted to respect people’s time. It is better to get it over with quickly, even if it is disappointing. We also used the telemetry to get some handle on how many CPUs would fail the NX requirement so we could be sure enforcing NX presence was responsible in the ecosystem. We learned that less than 1% of CPUs did not have NX capability available and configured correctly and out of those 0.1% did not have the NX capability at all. Based on this we feel that enforcing NX presence is a good thing to do since it results in better malware defenses. Thus we now enforce NX presence in the kernel boot sequence.

We didn’t make any change related to PAE detection, but it is good to note that PAE is a pre-requisite for NX on 32 bit processors due to how NX is implemented in memory manager page tables.

We did change SSE2 instruction set detection based on telemetry from the CP and Windows 7.

The result for users at large is their PC is more reliable. We do not check for SSE2 in the kernel boot sequence,;however, if your CPU has NX it also almost certainly has SSE2.

Workaround

Before trying this workaround, please check & configure NX in BIOS. The the workaround uses the ISO to install.

“Download the ISO and burn it to a DVD or create a bootable USB flash drive. Boot from the media that you created. If your CPU does not support NX you will see a code 5D bluescreen before setup starts. This is rare, but if it happens we won’t be able to help you run Windows 8.

This workaround may succeed because Windows contains two installers: the end user installer (setup.exe at the root of the Windows DVD) and the commercial installer (setup.exe found in the \sources directory of the Windows DVD). The commercial installer runs when the PC is booted from DVD/USB media and does not perform the NX/SSE2 checks and attempts to enable NX/SSE2 on supported systems.”

This issue has been explained in detail by Microsoft. If someone getting this error, he or she can refer this and try the workaround.

Posted by on , in Category Windows with Tags
The author is a Microsoft MVP, a Technology Enthusiast and a Mechanical Engineer. He is interested in anything technical and is committed to Microsoft technologies and products. He is actively associated with various Microsoft online communities, forums, Newsgroups and has been actively involved in Beta testing various Microsoft products and bug submissions.
  • Myothernamesagoodone

    Oh, super! So now they don’t only want you to buy the new OS but also get a new computer to run it? Did they learn nothing from disasters like ME and Vista? Or are they so utterly wrapped up in their ivory tower now as to give not a damn about what anyone thinks of their little pet project?

  • http://www.facebook.com/profile.php?id=1390076509 Ferry Indrapratama

    O/S for gadgeteer & gamers

  • kyleburns

    @Myothernamesagoodone:disqus your reaction may be more extreme than necessary. For this particular processor capability, Intel added it as far back as the P4 because AMD was already implementing it in their processors. Most users running XP today have the capability and I would venture to say that anyone running hardware that pre-dates this feature being the norm is not likely to be paying for an operating system upgrade.

  • http://twitter.com/rover3500 simon

    Technology goes forward tho’ doesn’t it?It wouldn’t change much obviously otherwise.U wouldn’t expect a biplane to go to the moon for instance

  • Myothernamesagoodone

    That’s fine if they market W8 as an alternative OS for new(er) computers rather than a replacement for W7. Nothing suggests that that’s the intention however.

  • Waleed

    I have the same probem, and I tried to solve it with no successe

  • Hjo

    I am sorry to say but your explination is not compleet. The error can come on even a faily new CPU (Intel Core 2 Duo E6750) which is fulfilling all requirements (veryfied by Coreinfo.exe). I am unable to find out what is the reason for that incompatibility

  • Vasudev

    Tried the workaround? Checked the BIOS settings?

  • hardy

    Hi, Vasudev,

    did I understood you correctly, that the proposed workaround is, to boot into setup from DVD / USB Stick?

    I thought, this is the standard procedure…

    I am still having an error then: “your computer needs to be repaired…”

    It is confirmed, that my pentium-M 745 has no PAE.

  • Shahrukh

    even i do have a intel dual core processor and it is still showing the same error again and again, what is the resolution for that ……????

  • Bsg017

    I have a problem with coreinfo.exe because the display is transient and does not allow me to read it – is this common?
    According to the BIOS display, I have NX enabled and hence my reading of the above is that PAE and SSE2 should be too.
    But I have found that the ability to navigate the BIOS screens seems to be failing and perhaps this is affecting Windows 8 although it has not affected the normal operation of Windows vista – perhaps a new battery will be called for!

  • FaizanAliNaqvi

    Please someone help me i have a Pentium D 945 3.4 GHz, Coreinfo shows that my PC supports VT-x and Hyper Threading i was like WTF, But then some one told me Coreinfo had wrong information for my CPU, Please someone confirm if my PC supports NX Bit, PAE…………SSE2 is enabled because CPU Z shows it is.

  • Dubisthasslich

    move it to your root (C or D or whatever drive letter-the default OS partition), then open up cmd, type cd C: and then type coreinfo

  • Ace3d
  • FaizanAliNaqvi

    THANKS MAN one more thing, What graphics card is best for my Dell Motherboard.

  • anon2012

    I have not used coreinfo, but maybe create a small batch to send the information to text file. just one line in the .bat file should succeed:
    coreinfo.exe>coreinfoOut.txt

  • anon2012

    you have 5 paragraphs under subheading “workaround”
    If I understand, then the 3rd paragraph implies that the workaround to avoid the nx/xd check is to use “commercial installer” setup.exe

  • Johan Austad

    Hi,
    In the post you say, “If your CPU does not support NX you will see a code 5D bluescreen before setup starts. This is rare, but if it happens we won’t be able to help you run Windows 8.”

    But we has problem that windows installer starts and install windows, but after installation when it are finished installing and windows restarts the computer, then we get this 5D error. And text saying we have to use power bottom to restart the pc.

  • Randal Gossip

    This works Thanks . The results show the CPU supports SSE2 but I still cannot update chrome.

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