The Sapphire HD 4890 manages to offer some serious power thanks to the massive 1000MHz core on offer which is way up on the already high 850MHz that a reference clocked card follows. It's also great to see that Sapphire hasn't just stopped with the core but also decided to ramp up the memory speeds which continues to help improve the overall performance of the card.
This serious performance comes at a cost, though, and you're looking at around 20% - 30% more expensive than a stock clocked model. What that extra money gets you is a better bundle than your standard base model, a better cooler that runs quieter along with a nice jump in performance.
If you want some serious speed, a quieter running card and don't mind spending the extra dollars, the ATOMIC version of the HD 4890 from Sapphire is an absolute awesome buy. If you don't want to spend that much yet still want a bit of a performance increase along with a new cooler, it might be worth looking at the TOXIC or Vapor-X version of the card which doesn't carry the high price tag.
All in all we've got a pretty kick ass card here and if you're looking for a top of the line HD 4890 this is the one worth looking at. In typical fashion Sapphire hasn't disappointed and makes good use of the ATOMIC name once again.