Had a client today whos SCCM 2012 PXE enabled DP wouldn’t work. Upon inspection of the SMSPXE.log file I saw:
Warning: Matching Processor Architecture Boot Image (0) not found
SCCM PXE requires you to have both x64 and x86 images deployed even if you aren’t going to use both of them.
For both of your boot images, ensure ’Deploy this boot image from the PXE service point’ is ticked and then make sure you ‘Distribute Content’ to your PXE enabled DPs.
Then check your RemoteInstall\SMSImages directory for the new WIM and the SMSPXE.log file to see if the new WIM is loaded.
More info here - http://technet.microsoft.com/en-us/library/hh397288.aspx