I've got a problem with my Late 2011 17" MacBook Pro. On Startup I get a thin Multicolour Band Appear Horizontally across the screen above the apple logo. This is then followed by the screen going black for a few seconds. It then continues to boot normally and logs in fine. I've recently been to the Apple store and had the Logic Board and GPU replaced as part of their warranty extension programme. It happened before the replacement, and is what prompted me to look into the replacement in the first place. When i received it back i questioned them further as it was still having this problem. After checking the laptop again they said that this happens on all of these models of MacBook pro. To be honest this surprised me, as it certainly isn't normal behaviour on any other mac i've seen. Plus it never used to happen on this mac until a few months ago. My Question is... Has anyone else experienced this problem, and if so were you able to resolve it? I've included a picture to help describe the issue. Its a late 2011 MacBook Pro 17" 1TB SSD, 16GB Ram Running macOS Sierra.