After recently removing a faulty Gigabyte 7970 I assumed my integrated graphics would come back on, except it hasnt, cant be found under device manager etc. (i5 3570k)
In your BIOS, go to Advanced > System Agent Configuration > Graphics Condiguration.
Primary display should be set to auto. If it is, try setting it to IGPU and reboot. If that fails, try setting the Initiate IGPU option to enabled, under the same menu.
What motherboard do you have? Often there are settings in the BIOS that are automatically disabled once a discrete GPU is detected. Look for something related to IGP.
In your BIOS, go to Advanced > System Agent Configuration > Graphics Condiguration.
Primary display should be set to auto. If it is, try setting it to IGPU and reboot. If that fails, try setting the Initiate IGPU option to enabled, under the same menu.