When testing the maximum stable overclocks in Battlefield Bad Company 2, we found the HD 6870 IceQ X Turbo X was 6% faster. The HD 6850 IceQ X Turbo has more ample gain room as it received a 14% performance increase versus the factory overclock.
The HD 6870 IceQ X Turbo X was just 2% faster in Crysis Warhead once we overclocked further, while the HD 6850 IceQ X Turbo was 14% faster.