Newegg doesn't have warranty information for the products so I went on their respective websites. Sapphire has a 2 year warranty and VisionTek has a lifetime warranty. PowerColor....lets just say they don't like to share that information. Can't find warranty info in the FAQ and the Warranty page is total mumbo jumbo. Anyone know of the PowerColor Warranty?
not always, thermals (pastes, material quality) and the way the heating is setup is different. performance wise you should get the same thing.
Powercolor is def not a brand I would recommend, my Powercolor X800 XL crapped out on me 3 times (3 warranty replacements, and they still haven't fixed it so I gave up). Personally i went for Palit for my 4870 X2. First 1 was defective but the 2nd one works great.
So your choices would be saphire or Palit I would say.