Buying a Radeon HD 7870....

djscribbles

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Apr 6, 2012
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If you crossfire a fast card with a slow card, the slow card won't really do anything at best, at worst it will slow down the fast card.

The 7870 destroy everything at 1080p by itself anyway, even if the two were additive, the 6570 probably wouldn't be worth the extra power consumption.