What I saw was a completely working operational PC that would "boot loop" if we unplugged the GPU.
Fixes have been:
1. Uninstall the GPU's drivers (The Nvidia, use this tool. http://www.bleepingcomputer.com/download/display-driver-uninstaller/ )
2. Wipe out and start over with the OS.
3. Boot Safe Mode and remove the Nvidia in device manager, etc.
I am able to boot into Windows just fine, whether I am plugged directly into the mobo, or my GTX graphics card. Either way I use HDMI.
When I try to boot after removing the graphics card, I am completely unable to boot, just plugged into HDMI on the mobo.
When I DO try to boot this way, the machine gets stuck in a reboot loop with no errors, as soon as booting begins for the main hard drive, an SSD, the machine immediately reboots.
-resetting bios to default
-uninstalling nvidia drivers
-making sure Intel HD graphics driver is installed correctly, it is
-booting with just VGA-booting into safe mode
-Enabling and disabling multi monitor support
- selected IGFX under Primary Display in Bios
All steps failed to resolve.
I have a suspicion that the graphics controller on the mobo is the cause? or the settings or driver related to it? why would I otherwise need a dedicated card plugged in to boot through Intel HD Graphics 3000 with HDMI plugged into my mobo?
OS Name Microsoft Windows 7 Home Premium
Version 6.1.7601 Service Pack 1 Build 7601 x64
Main drive: 256GB SSD
Graphics Card: EVGA Nvidia GTX 970
Motherboard: Asus P8Z68 PRO/GEN3
CPU: Intel i5-2500K / iGPU Intel HD Graphics 3000
RAM: 16GB DDR3
Monitor: Single ASUS 1080p, connected with HDMI