I'm trying to return my Radeon HD 6870 which is breaking (The fan doesn't work, and it overheats). However when I remove it from the PC, and revert to using the HD3000 in my i5 2500k, it refuses to start Windows.
I run a Hackintosh, and when I select Windows, my PC just restarts. If I connect the GPU back up, without using it to drive any displays, Windows will start.
I have tried reinstalling then uninstalling the Catalyst drivers, but it doesn't seem to have helped.