ESXi 4.0 or 4.1 displays the message: “TSC: 2735818866 cpu0:0)Init: 461: The Execute Disable/No Execute CPU feature is not enabled for this machine” on the console

The error message you see may vary as I find that other text tends to overlap the error message such as this which was displayed on one of our servers when you hit the ALT+F11 key from the main ESXi screen:

If you see this message, you’ll need to poke around the BIOS and depending on the type of server, look for a feature that is similar to:

No Execute Memory Protection

… and then set it to Enable.  Here’s an example of what it looks like on an HP ProLiant DL380 G5:

Press F9 during the POST screen to get into the BIOS:

Select: Advanced Options:

Select: Processor Options..:

Select: No-Execute Memory Protection:

 

Notice how the bottom box says Disabled?  We need to change that to Enabled so it displays the box as such:

There isn’t an F10 option for HP’s BIOS so hit ESC a few times to exit the BIOS.

Now when you reboot ESXi and hit ALT+F11 after all the server completes the boot up process, you should no longer see that message:

I won’t go into the details as to what this function does because I would not do as good as a job than other websites so here’s a link to Wikipedia that would get you started: http://en.wikipedia.org/wiki/NX_bit.