And he said chips handle these cases, no driver need to somhow check for those. I gueesed that maybe that "Stencil op fail or zfail is not KEEP" is culprit but who knows :) http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Depth_in-depth.pdf#6 http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Depth_in-depth.pdf#10