There are 2 cards that I'm currently looking at. Both are HIS IceQ X Turbo cards but one is a 6850 while the other is a 6870. The 6850 is $158 while the 6870 is $188. Is the 6870 worth the extra $30? If so, are there any references or benchmarks that I could look at to compare the 2? I have a i5-2500k, 16GB DDR3 RAM, and a 850W PSU. My monitor runs at 1600x900 and I don't plan on buying a 1080p one until it burns out or something along those lines.