Although the Radeon HD 5770 was slower than the GeForce GTX 260 and Radeon HD 4870 at all three resolutions, the margins were relatively small and still allowed for very playable frame rates.
In fact, at 2560x1600 where the Radeon HD 5770 rendered an average of 74fps, the Radeon HD 4860 was just 2fps faster and the GeForce GTX 260 5fps faster. This meant at this extreme resolution the Radeon HD 5770 was just 6% slower than the GeForce GTX 260.
When testing with S.T.A.L.K.E.R Clear Sky we see quite different performance trends at 1680x1050 and 2560x1600, as graphics cards with smaller memory capacities appear to suffer when using extreme resolutions.
As a result the Radeon HD 5770 is just 13% faster than the Radeon HD 4870, while it extends this lead to an impressive 35% margin at 2560x1600. Furthermore, at this resolution the Radeon HD 5770 is just 1fps slower than the GeForce GTX 260.