I found this reference:
This document describes the products that can be affected, problem description, cause and workarounds. This issue is fixed with BIOS 01.02.0009 or later.
So, you could disable your internal video to test, and/or verify your bios version.
Hope this helps
When you connect to a single slot PCI video card is specified, but when connected to the second PCI expansion slot is not defined. As if one the expansion slot is not active or enabled. The BIOS can't find the setting that enables or disables the PCI expansion slot. In the first expansion slot PCI fails to connect because the video card does not fit because of its size, as there is already a RAID controller, and the second PCI expansion slot free.