The best aftermarket GPU coolers for the 6870 are the: Arctic Cooling XTREME Plus II - 45.99
GELID Rev. 2 ICY VISION - 42.99
Both GPU coolers are great. Personally I prefer theArctic Cooling XTREME Plus II because it has three 92mm fans that keep the GPU silent and cold. The GELID Rev. 2 ICY VISION is a cheaper option and has uv reactive fans that also spin quiet. In conclusion, both GPU coolers are fantastic choices that will definitely beat the stock cooler. Any one is a great choice. It really depends on what your looking for like color, size, fan amount, and sound.