I understand now, but IMO that would make for a pretty awkward case, with the back of the GPU at the front of the case. I can't see it being very appealing without at least a cover, but then you've still got a video cable exiting the front... There's only so much you can do. Fans with a higher thickness to diameter ratio generally are able to generate more air pressure, and GPU fans are thinner out of necessity. They already have to push air through the restriction of the GPU heatsink, and then make a right angle as they hit the PCB, so they're already being asked to do a lot. Filters just make it that much worse. I agree that heat is a potential issue, which is another reason I favor the front-to-back layout that I've shown rather than a back-to-back layout.