Many people who tried to install Windows 8 Release Preview have reported that they are stuck with the error "Your PC's CPU isn't compatible with Windows 8". It has been confirmed that not all CPUs are compatible with Windows 8 RP. Even if you were running Windows 8 Consumer Preview, it is possible that you may not be able to run Windows 8 Release Preview on the same computer unless you have the NX bit enabled in your BIOS. Most computers have it enabled by default, but if not, you have to enable it manually from the BIOS.
The system requirements for Windows 8 RP does not mention that your CPU should support NX (or, XD or XN), but it looks like you need a compatible CPU with this flag enabled in the BIOS.
What is NX, XD and XN in the BIOS
This is a BIOS feature that allows you to enable or disable the Execute Disable feature of your CPU and can be configured only through the BIOS of your computer.
NX stands for No eXecute and is a technology used in processors to prevent execution of certain types of code. This was originally invented by AMD.
XD is the acronym for eXecute Disable, which is an Intel specific implementation of NX. It refers to the same feature but Intel chose to call it by a different name.
XN is the ARM equivalent of the same feature and is the acronym for eXecute Never.
Essentially, both NX, XD and XN are the same and are different names for the same feature in AMD, Intel and ARM respectively.
How to enable NX or XD in the BIOS
This flag can be enabled or disabled only through the BIOS of the computer. In order to enable this flag and make your computer compatible with Windows 8 RP, follow the steps below:
1. Restart your computer
2. While booting, before the Windows starts, press the key to go to BIOS. The key to open the BIOS is different for different computers. Most computers use the keys F2, F12 or DELETE. Try each of these keys and see if you can get to the BIOS. If none of those keys work, then one of the tricks I do is, press all the function keys (F1 to F12) repeatedly on the computer while starting the computer. Hopefully, that will work.
3. In the BIOS, go to Security tab.
4. Look for the NX or XD flag. In case of Intel processors, you will see the XD flag and in case of AMD processors, you will see the NX flag. If that is not enabled, toggle the option and enable it.
5. Save the settings and exit the BIOS settings.
6. Restart your computer.
Now try to install Windows 8 Release Preview. Since you have enabled NX/XD bit, you will not see the error Your PC's CPU isn't compatible with Windows 8 anymore.
NX and XD flags missing in the BIOS
The NX or XD flag is not available in all the BIOS programs. Many manufacturers are not showing this option in the BIOS. I tried a Lenovo Ideapad laptop and a Sony Vaio laptop. Both laptops have these options missing in the BIOS. I am still searching for a solution to this and I will post if I find anything. I found one of the forums that says we need to contact the computer manufacturer and get an updated version of the BIOS program to see the NX/XD bit flags in the BIOS. I am not sure how many consumers are going to take this pain and upgrade the BIOS program to install Windows 8 on their computer.
If the eXecute Disable feature is missing in the BIOS, there are few possible reasons:
1. You have an outdated BIOS program
2. Your CPU does not support NX/XD flag. This is modern feature introduced in newer versions of the CPU and may not be available in old versions of the CPUs. If you have an old computer, your CPU may not have this feature.
3. You may have an incompatible operating system. Only new operating systems like Windows Server 2003, Windows 2008, Windows XP, Windows 7, Windows 8 and new versions of Linux support the XN/XD feature.
Windows 8 Release Preview has a dependency on the NX bit of the CPU and you cannot install the Windows 8 RP unless the NX is enabled on your CPU.
If you tried the steps mentioned in this article and it resolved your error Windows 8 installation error, please let us know by posting a response below. If the above steps did not work but you had to do something else to enable NX or XD on your computer, share your experience and help others.
|Guest Author: Friedrich 01 Jun 2012|
|I went to my BIOS but I could not find any security tab. I found un der the advanced tab "security" mentioned but I could not find any flag you mentioned in your article. So, I have no idea how to go from here.|
|Guest Author: jorge Fernando 01 Jun 2012|
|in tried the steps on my BIOS with XD an is still the problem i dont know what to do :( my CPU is Intel dual core E6500 with XD Enable. in a motherboard ECS G31T-M9|
|Guest Author: bence 01 Jun 2012|
|compal ifl90, t7300 cpu, and cannot solve this problem :-(|
|Guest Author: UNKNOWN 02 Jun 2012|
|same here. if its not comatible, why don`t just microsoft make a windows 8 Reveiw Preview. That just make me sooo mad! :(|
|Guest Author: tidabblju 08 Jun 2012|
|I only have the option "PXE - allow/reset/deny" but I think thats not the NX or XD option. I cannot install W8 RP.|
(Dell Dimension 8300)
|Guest Author: Philippines 09 Jun 2012|
|can we enable it using cmd? |
i know PAE can, dunno if NX can, Thanks :).
|Guest Author: sylber 09 Jun 2012|
|I have install Everest and on security bios (see print screen )write :unsuported,can we activated with update bios or using cmd?|
my CPU is IntelPentium P4I65G,
|Guest Author: sachin 23 Aug 2012|
|when i install windows 8 on my pc then windws 8 setup screen show me "your pc's CPU compitable with windows 8 " my pc's configuration is Intel pentium 4 cpu 2.40 Ghz, 1.0 GB RAM, Mobile Intel 945GM Express Chipset Family.|
pls help me. my email id is firstname.lastname@example.org
please help me.
|Guest Author: nasus18 26 Aug 2012|
|Yes, please search for a solution for the no NX enable in bios in, my pentium 4 2.4Ghz CPU it can run Ubuntu 12.041 but unable to install win 8.|
|Guest Author: YEAH 28 Aug 2012|
|I know XD is same as NX right now.|
|Author: Krishna 30 Aug 2012||Member Level: Bronze Points : 2|
|I cant install win 8 RP on my PC|
The whole installation goes smoothly but at the time of reboot, the graphics get all messed up & it prompts "there was an error in installation"
"rolling back to previous version of win"
My PC config
8GB DDR3 RAM
AMD Phenom II X4 945 Processor
Gigabyte MB with DUAL BIOS (nVidia GeForce 7025/nForce 630a)
I've tried installing through DVD, USB.
& I couldnt find NX bit feature in my BIOS (my BIOS is updated)
|Guest Author: Mike 17 Oct 2012|
|There is no "security" tab on the bios screen on my machine, but XD is under the "power" tab|
|Guest Author: JD 30 Oct 2012|
|this came in handy, I went in and enabled XD but I wasn't sure if that was it .. so I searched the enable xd blah blah and found this which confirmed it.|
|Guest Author: or 20 Nov 2012|
|Msi board not security mentioned or nx or xd. What to do? Computer is new, board os x58proe i7-920 Intel.|
|Author: Juergen 10 Dec 2012||Member Level: Bronze Points : 0|
AIDA32 will show under CPUID wether NX is supported or not.
Everest home does not?
So, before before searching your BIOS use AIDA.
|Guest Author: Frank 15 Dec 2012|
|On my MSI board, with a Phoenix-Award BIOS, the setting can be found in:|
"Advanced Features" next to Speedstep and S.M.A.R.T. Settings called :
"Execute Bit Support", which by default, at least on this board, is set to off.
Maybe this will help some people looking for it.
|Author: BOB 09 Jan 2013||Member Level: Bronze Points : 0|
|PLS HELP ME I HAVE NO XD/NX IN BIOS!!!!!!!!!|
Ih have intel i5 2. Generation
and Lenovo Ideapad
PLS HEEELLLLP MEEEE!!!!!!!!!!!!!!!!
|Guest Author: Dmitriy 22 Jan 2013|
|Thanks for your advice. I have a question if I simply change my processor, which supports XD should it be then fine? If it is then what should I be aware of or follow a certain rules?|
|Guest Author: J R 31 Jan 2013|
|On my computer:|
Enter setup at load up (BIOS)
under ADVANCED tab
select >CPU Configuration, press enter
Then in list, is
> No-Execute Memory Protection
Mine was diasabled, Enable and all is good
|Guest Author: Tiago Coelho 17 Feb 2013|
I have a Lg s1-m55p laptop with a t7600 processor, bios: rkywsf33.
My nx option was under ADVANCED tab, called: No Execute Mode Mem Protection.
Just enable it and it worked.
|Guest Author: wadupola wimala dass 11 Jun 2013|
|i search it but there is no NX. plz create a software for update bios in pentium 4 to install window 8. thank you|
|Guest Author: manoj kumar shahi 18 Jun 2013|
|plz give me detailed information how to enable nx bit and if how to update bios to get nx bit. bios brand=American megatrends inc. version=080015.date 06/02/2010.memory ram 2GB ddr2. processor intel pentium 4 520. 2.80GHz|
plz these above details are my computer details sir.
if there is no nx bit any solutions for installing windows 8
|Guest Author: mdesign 04 Jul 2013|
Thanks great explanation
ASROCK z68 Extreme 4 Gen 3
Click CPU config
Choose last option change to enable