First thing you should be doing is asking these questions on the Sapphire forums because AMD cannot help you with a replacement, obviously, if it comes to that...;) You may run into people who had your problem and solved it. But, based on what you've said, I would first drop all GPU clocks back to stock OC in case you have OC'ed them higher than factory and see what happens. When you buy a factory overclocked card the general rule is that it comes already overclocked to its maximum speed--and often you will be lucky to get 10Mhz additional clock without problems of some kind. Your Nitro is a factory OC'ed card. Artifacting during 3d games is generally a sign of a physically bad card (ram, GPU, etc.), which is rare, but it does happen. However, If you are only artifacting running certain 2d video clips, but not in your 3d games, then it's likely you have a software problem--likely with your OS--that is causing it--bad OS codec, browser problem, etc. My 590 8GB XFX Fatboy is completely free of such problems, even OC'ed to 1.6GHz (factory overclock.) But if I OC to 1.610 GHz, problems appear. Same is true for my 8GB RX-480--it's factory OC'ed to 1.305GHz--and runs fine all day--but if I pour on 10 more MHz--I get problems. What's great about factory OC'ed cards is that they are fully tested to run 100% at their shipping OC'ed speeds--if the OEMs could get them to run faster without problems, believe me, they would do so...;)
