I think a good opportunity would be to add faster memory chips or even G5X for the 580. Would get pretty big performance increases, or more so from that since it's likely the core clocks won't get much higher
Death is just another path, one that we all must take.
The grey rain-curtain of this world rolls back,
And all turns to silver glass, and then you see it...
White shores, and beyond,
A far green country under a swift sunrise.