So i am buying it and need to check for defects. (Local reseller offers replacement for only 5 days after purchase) I haven't owned Mac in the past so please recommend what should i check when i buy it. (F.e. on windows laptop i'd check screen on white/black backgrounds for dead pixels or damaged spots, run prime95 , furmark, windows disk and ram tests and temperatures when running 3d mark... ) So which programs are used to test macbook hardware for defects and what should i be looking for?