HP DL380p Gen8 Server won't boot after installing Hyper-V Role

[DoJu]

Hi Everyone

Has anyone noted out in the field HP DL380p Gen8 Servers not booting after installing the Server 2012 (NOT R2) Hyper-V role? 

Here in our test lab, as soon as I installed the Hyper-V role and rebooted, Server 2012  will not start (not even a BSOD) just a blank screen. The PROD Server is Server 2012, so we have to replicate in the test lab for DR purposes.

Product ID: 642120-371 BIOS is P70 07/01/2015 

Intel VTPro etc enabled in BIOS. 

It has a HP D2000 Disk Enclosure attached (PN AJ941A) and that initializes the 24 disks without issue.  I can't see anything in:

HP ProLiant DL380p Gen8 Server - Product documentation

http://h20195.www2.hp.com/v2/default.aspx?cc=us&lc=en&oid=5177957

Any ideas / resolutions most appreciated!