Solved : Upgrade fails with NX bit not supported error on CPU with NX, PAE and SSE2 support as verified by MS coreinfo tool.

You might want to check if there are any BIOS updates available for your system and apply them then try updating again.

Found a fix. In my case, setting "Execute-Disable bit capability" option in the bios to disable allowed the setup to work just fine. Dont ask my why i tried it or why it works. Its the exact opposite of what i expected, but it works!

For the record, i was on a toshiba t135 laptop with a intel su4100 chip and the latest bios.

RamRV_483, thanks very much for reporting your finding. The counter-intuitive step of disabling the Execute-Disable option in BIOS also allowed me to proceed with Windows 10 installation. Perhaps there is an extra or missing negation in some branch of the installer's test logic.

My original post:

http://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/you-cant-install-windows-10-because-your-processor/90ad5b3f-7a4b-49a2-8788-57a9dbd29ba4

Disabling the "Execute-Disable" option in the BIOS worked for my HP Mini 5102 Netbook with Intel Atom N450 processor.  That processor was reported as working great for the Windows 10 previews, and doing a clean install works just fine.  Trying to do an in-place install for the "free" Windows 10 upgrade/activation as well as the Get Windows 10 app fails on every attempt with "Incompatible CPU" and the "NX" not supported error until I tried this.  It is counter-intuitive but it works.  I left the execute-disable in Windows 7 Pro advanced settings turned on, that didn't apparently matter.  It's all in how the BIOS is configured.

I'm very happy to see this suggestion worked!  I'm not sure how to add more keywords so this post is easier to find in search engines for other people trying to upgrade Netbooks and other older processors in the future.  This suggestion belongs in the Windows 10 upgrade FAQ!

I have a Samsung N150 Plus netbook with an Intel Atom N555 processor.  Changing the EDB (Execute Disable Bit) from Enabled to Disabled in the Advanced section of the BIOS worked for me too.  Before that I would get a message saying that my computer could not be upgraded because my CPU does not support NX.  This happened pretty soon after starting the upgrade.  After the setting was changed the installer ran to completion.  Windows 10, once installed, does not seem to mind which way that BIOS setting is set.

It seems there is a fault in the installer when it deals certain processors.  I wonder if Microsoft knows about this?

I am attempting this now on my Dell Inspiron 530s. It has succeeded (finally) in getting past the PC check. Dammit, I could have been running windows 8.1 all this time as well. It failed for the same reason.

My question now is, do I re-enable the Execute Disable Bit in the Bios after the upgrade finishes?

I should invoice Microsoft for the time I've spent stuffing around on this computer and in Google going over articles about ensuring NX was enabled.

Microsoft hasn't been bought out by Walt Disney recently has it, and I just haven't noticed? As this sure smells of Mickey Mouse Operation to me.

There should always be an "install anyway, I've damn well checked the compatibility myself" button. Followed by the usual "are you sure"

I provide the above comments light heartedly for amusement purposes of course, considering how many PCs I've upgraded, overall things have gone very smoothly. :)

There's the magic word "Dell". I once saw a post on a forum, that said something along the lines of, if you have exhausted all troubleshooting options and it still doesn't work, then "Dude you gotta Dell". 

Haha truer words were never spoken. I have 3 computers that are giving me trouble. 2 of them are Dells (Inspiron 530s) and a laptop that needs a bios update first (but won't do it until I replace the dead battery) the third, believe it or not is the Surface Pro (1st gen). All my HP laptops have cutover smoothly.