Is there a way I can verify my MacBook Pro (Early 2011) is using the AMD drivers instead of the on-board video? Background: Like many, my MBP developed the video problems with this model with the monitor going blank. I was able to reboot using a suggested workaround: single-user mode, and moving all of the AMD/ATI drivers out of System:Library:Extension. In single-user mode, the video was very poor, of course, and as it reported, the MBP could not go into sleep mode. I sent the MBP into a third-party which does component repair on logic boards. Got it back via shipment, and I was able to boot into standard multi-user mode. However, the video quality is still poor (constant refresh in Finder windows, for example). And I still can't put the MBP to sleep. I reinstalled the AMD/ATI drivers I had temporarily removed, fixed permissions on them, and zapped PRAM. However, no improvement. The repair firm has offered to look at the MBP again under warranty. However, first I want to verify that the software really is using the AMD drivers. The video display is so similar to when I was in single-user mode that I have my doubts. Thanks for any help.