SCCM 2012 – How to increase TFTP / PXE boot speed

By default, System Center Configuration Manager 2012 use a small TFTP block size, 512 bytes. This behavior is set to be compatible with all network configuration, but the result is that the PXE boot speed can be slow using Operating System Deployment with SCCM.



We can resolve this problem by adding a registry key on the PXE Server. Modification must be made on PXE Distribution Point.

Boot speed

To increase the PXE boot speed, we need to modify TFTP Block Size.

  • In the registry editor:
    • Name : RamDiskTFTPBlockSize
    • Type : REG_DWORD
    • Value : 16384 (decimal)
SCCM RamDiskTFTPBlockSize

SCCM RamDiskTFTPBlockSize

SCCM PXE boot speed registry key

SCCM PXE boot speed registry key

Note:  16384  is the maximum supported value. If it is bigger, you can have corrupted data. However I recommend to do some test with values :4096, 8192, 16384. Depends on your network configuration, a lower value can be used.

  • Restart the Windows Deployment Services Service. (WDS)
Restart WDS

Restart WDS


You can have more information about SCCM and PXE here.


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