It should be fine with the HD6870 as well. The only time it will be a bottleneck is when games are multithreaded which is very few. I see in your other post that you are upgrading from HD4890 which is still a powerful card. Anything less than a HD6870 would not be a notable upgrade http://www.techpowerup.com/reviews/HIS/Radeon_HD_6870/29.html