Long story short, there's a stored procedure in the SCCM database that does some bad math to calculate the uniqueness of a SMBIOS GUID. This had me stumped for a week, and finally found probably the only other person on the planet that was having the same problem. Problem solved by adding a few bits to 3 stored procedures.

http://www.windows-noob.com/forums/index.php?/topic/5903-pxe-aborted-only-with-one-client-ive-checked-everything/

NBS_LookupDevice

Find the line

On xref.machineid = aux.itemkey and aux.smbios_guid0 = @smsbios_guid

Change to

On xref.machineid = aux.itemkey and aux.smbios_guid0 = @smsbios_guid + '.'

NBS_LookupPXEDevice

Find the line

On xref.machineid = aux.itemkey and aux.smbios_guid0 = @smsbios_guid

Change to

On xref.machineid = aux.itemkey and aux.smbios_guid0 = @smsbios_guid + '.'

MP_GetClientIDFromSmbiosID

Find the line

Where (m.smbios_guid0 = @vchsmbiosid) and (isnull(m.obsolete0,0) != 1)

Change to

Where (m.smbios_guid0 = @vchsmbiosid + '.') and (isnull(m.obsolete0,0) != 1)

Big thanks to Moto

What's this all about? Symptom: Using SCCM to deploy Windows 7 with PXE to "Unknown Computers". We had everything configured correctly. MICROSOFT had a bug in their SP :)

nerdymark posted a photo:

nerdymark posted a photo: