Recently at my new workplace, we’ve been having issues getting new Lenovo ThinkCentre M700’s to (Legacy) PXE boot. The lights on the NIC actually went out when it tried to PXE boot! (Booting from a boot USB thumb drive worked fine.) Some folks out on the SCCM Subreddit (https://www.reddit.com/r/SCCM/) were having similar issues with various systems based on the new Skylake chipset, like our small Lenovo M700’s.

After someone on the Subreddit stated that they successfully PXE booted using a 100mb unmanaged switch as a workaround, I decided to investigate. I worked with one of our (Cisco) Network Engineers to test changing settings on one of our switch ports. He suggested disabling POE (Power-Over-Ethernet) and his idea was spot on. The new M700 was able to PXE boot after he made the change!

I haven’t seen anything official from Lenovo on the issue, but testing disabling POE on a port is worth a shot if you’re in a similar situation.

Lately, I’ve been working on a project to deploy a customized Windows 7 MDT task sequence via SCCM 2012 OSD. We had questions re: PXE boot image handling and selection- specifically how SCCM OSD PXE would handle multiple boot images (especially of the same platform.)

We created a new customized (x86) MDT boot image for the project, and had not made it available to PXE. Our old existing (non MDT) x86 and x64 boot images were PXE enabled. Since the new task sequence was using a new boot image that was not available to PXE, after we deployed the TS to the “All Unknown Computers” collection, our PC Technicians were no longer able to image new/unknown systems via PXE. Whoops!

When a system PXE boots, SCCM basically determines which task sequences are available to it, and picks the boot image referenced in the most recently deployed task sequence. If the task sequence you then select uses a different boot image, the system will download it and boot up into it after restarting. In our case, I suspected that Unknown Computers could no longer PXE boot, because the most recent task sequence deployed to that collection was referencing a boot image that was not available to PXE. For more detailed explanation see these posts:

http://blog.configmgrftw.com/boot-image-selection-configmgr/

http://blogs.technet.com/b/michaelgriswold/archive/2012/01/12/which-winpe-will-you-get-from-a-pxe-boot.aspx

We decided to PXE enable the new custom (x86) MDT boot image (by checking the “Deploy this boot image from the PXE-enabled distribution point” checkbox on the “Data Source” tab of the boot image.) I wanted to see what would happen to the old existing x86 boot image.

I checked the \RemoteInstall\SMSImages\ folder structure on our SCCM PXE DP server, and verified that a new folder had been created with the new boot image’s ID. The other x86 and x64 boot image folders were also there.

During testing we confirmed that systems PXE booted with the expected (most recently deployed) boot image. So, the two different x86 boot images coexist just fine on the same PXE server. (We will most likely switch the old task sequences over to use the new MDT boot image in the future, but wanted to keep them both around for now.)