WDS: EFI BIOS won't PXE boot into EFI mode

I need to be in UEFI mode when PXE booting from WDS, but device comes up in BIOS mode.  I am using latest Win 2008 Server R2, fully patched.  The board manufacturer insists that the 'Legacy PXE option ROM' is capable of PXE booting into UEFI mode, but I have doubts.  For testing, I am using a x64 boot.wim and install.wim extracted from a recent Breckenridge (Windows Storage Server) DVD.  How do I know I'm not in UEFI mode? 

When booting PXE/WDS:

1. Windows setup is not able to create a partition greater than 2TB on a 3TB drive.

2. In \Windows\Panther\setupact.log I see:

            Callback_BootEnvironmentDetect: Detected boot environment: BIOS

When booting from a DVD (I have two choices in BIOS for DVD device, one specifies 'UEFI')

1. Setup creates a full size (2794 GB) GPT drive partition on a 3TB drive.

2. In \Windows\Panther\setupact.log I see:

            Callback_BootEnvironmentDetect: Detected boot environment: UEFI

In both PXE and DVD boot, I specify drivers when setup presents the 'install drivers' button, so that the full size 3TB is displayed.  Diskpart shows the following after PXE installation:

DISKPART> list disk
 Disk ### Status  Size Free Dyn Gpt
 -------- ------------- ------- ------- --- ---
 Disk 0 Online  2794 GB 0 B
 Disk 1 Online  482 MB 0 B
 Disk 2 Online  465 GB 0 B

DISKPART> select disk 0
Disk 0 is now the selected disk.
DISKPART> list part

 Partition ### Type  Size Offset
 ------------- ---------------- ------- -------
 Partition 1 Primary  100 MB 1024 KB
 Partition 2 Primary  60 GB 101 MB
 Partition 3 Primary  1987 GB 60 GB

Apparently setup did not detect UEFI, and created an non-GPT disk.  I thought maybe there was something I had to specify on the WDS side, but found nothing in the GUI.  I did find options inwdsutil to display and set a 'default boot program' for specific architectures (my target architecture is x64).  WDSUTIL /get-Server /server:SVR.Foo.local /show:Config shows:

Boot Program Policy:

 Known client PXE prompt policy: OptOut
 New client PXE prompt policy: OptOut
 Allow N12 for new clients: 
 Architecture discovery: Enabled
 Reset boot program: No
 Default boot programs:
  x86 - boot\x86\pxeboot.com
  x64 - boot\x64\pxeboot.com
  ia64 - boot\ia64\bootmgfw.efi

 Default N12 boot programs:
  x86 - boot\x86\pxeboot.n12
  x64 - boot\x64\pxeboot.n12
  ia64 - boot\ia64\bootmgfw.efi

So I tried changed the default boot program for x64 to (using WDSUTIL /set-Server /BootProgram:boot\x64\bootmgfw.efi Architecture:x64), to look like:

Boot Program Policy:

 Known client PXE prompt policy: OptOut
 New client PXE prompt policy: OptOut
 Allow N12 for new clients: 
 Architecture discovery: Enabled
 Reset boot program: No
 Default boot programs:
  x86 - boot\x86\pxeboot.com
  x64 - boot\x64\bootmgfw.efi
  ia64 - boot\ia64\bootmgfw.efi

 Default N12 boot programs:
  x86 - boot\x86\pxeboot.n12
  x64 - boot\x64\pxeboot.n12
  ia64 - boot\ia64\bootmgfw.efi

But I got the same result (Setup cannot configure > 2TB partition, setupact.log shows 'BIOS' boot environment).  Am I missing something?  Should this work?

Thanks,
Dave