Tweaking PXE boot times in SCCM version In Configuration Manager we have option to tweak our PXE boot times, TFTPWindowsSize which we can change in the registry on our PXE enabled DP’s.

This is new version for SCCM TFTP Changer. What’s new:

  • New button Remove keys;
  • Nulled items don’t work, you must choose from drop-downlist for both parameters.

PXE booting a machine can never be fast enough!

Name: RamDiskTFTPWindowSize

The default value is 1 (1 data block fills the window)

We can also tweak the TFTPBlockSize which has been around for many versions of Configuration Manager.

Name: RamDiskTFTPBlockSize
Value: <customized block size>

The default value is 4096 (4k).

What we know for example:

  • That HP Probook for instance doesn’t support a higher TFTPBlockSize value than 1456 otherwise it freezes.
  • Vmware 5.x doesn’t support a higher value for TFTPWindowsSize than 8.

I put together this list that could be a good starting point when testing out the different TFTP:

Conclusion UEFI boot is slower! and the values used will be different for many customers as there are now optimal values that will be best in all environments.

“Changing the TFTP settings was really boring so when I did the tests I wrote this little powershell tool as well to help in setting the values. I am planning to update it next week to be able to use it on Remote DPs and some more error handling. But you can use it as it is now to do you your testing. Run it as administrator so you have the permisisons necessary to change the registry values.”

PowerShell code from

I’m recreate this tool from powershell to app.

P.S. Run as administrator