I just started looking in to overclocking my GPU on my 15" MBP on my Windows 7 partition and I have yet to successfully do so. I'm trying to use ATI tray tools and everytime I try to increase my GPU frequencies and then hit "Apply", my screen goes black. I have the latest ATI driver software (11.9). And I have a 6750m graphics card. I also tried using MSI Afterburner but it doesn't even let me set my frequencies above the stock specs for core/mem. It is right now clocked at 600 for core and 793 for mem.