With this method you don’t have to import a computer in SCCM 2012 with the MAC-Address.
Just start the tasksequence as an unknown computer …
To do this, complete the following steps, if you need any assistance, just post a comment at the bottom of this post.
Open your Configuration Manager console and go to the Assets and Compliance Workspace and then click on Device Collections.
Right click on the collection you want to deploy the OS to then click Properties (for this guide I’m using All Unknown Computers). You then need to click on the Collection Variables tab.
Click on the new button as circled below:
In the variable name type OSDCOMPUTERNAME and leave the value areas blank and then click ok.
Once you have this collection variable in your collection property settings, you can then deploy your OSD task sequence to this collection and you will be prompted to enter your computer name.
– See more at: http://www.techygeekshome.co.uk/2012/12/prompt-for-computer-name-during-sccm-osd.html#sthash.5fguzzbD.dpuf