To overclock today we tried various tools, and settled on MSI's Afterburner, or Rivatuner as it is better known.
We had a real problem overclocking the Zotac GTX 580 AMP²!, failing to get anything more from the core. Even at 820mhz it would hardlock the system in 3DMark 11 and 3DMark Vantage. Overclocking really is the luck of the draw, but at least it shows that Zotac aren't hand picking the cards sent to reviewers. We are absolutely certain that if you bought this card it would overclock considerably better than this one.