Far Cry 2
This is a revolution indeed. The Radeon HD 4770 delivers the same performance as the Radeon HD 4850 at resolutions up to 1680x1050 inclusive. It is only at 1920x1200 that it loses its ground, being limited by its memory subsystem, but remains as fast as the GeForce GTS 250 512MB anyway.
When talking about practical play, the Radeon HD 4770 is limited to 1280x1024 in this game at highest settings together with 4x FSAA. Note that the newcomer has a higher bottom speed at that resolution than the Radeon HD 4850. This is an excellent result for a graphics card with a recommended price of only $109.
F.E.A.R. 2: Project Origin
The Radeon HD 4770 is 6-7% behind the Radeon HD 4850 even at 1920x1200. Moreover, the new card provides higher comfort at the latter resolution as it has a higher bottom speed. The RV740-based solution even beats the RV770-based one when overclocked!
The best result in this test is from the GeForce GTS 250 512MB, yet the Radeon HD 4770 delivers comfortable conditions at resolutions up to 1920x1200, too, while being somewhat cheaper.
Left 4 Dead
The game runs on the Source engine and has an integrated benchmark, but the latter does not report the bottom speed information.
As opposed to most other tests, the difference in performance between the Radeon HD 4700 and Radeon HD 4830 is no bigger than 7%. However, the new card from ATI is fast enough for playing at 1920x1200 together with full-screen antialiasing. When overclocked to 860MHz GPU and 975 (3900) MHz memory frequencies, the new card becomes as fast as the Radeon HD 4850: a little faster at low resolutions and slower than it at high resolutions.
S.T.A.L.K.E.R.: Clear Sky
To achieve a playable speed in this game we disabled FSAA and such resource-consuming options as Sun rays, Wet surfaces and Volumetric Smoke. We use the Enhanced full dynamic lighting (DX10) mode for our test and additionally enable the DirectX 10.1 mode for the ATI cards.
S.T.A.L.K.E.R.: Clear Sky shows that the performance of the Radeon HD architecture depends greatly on frequency: the Radeon HD 4830 has no chance against the Radeon HD 4770. The latter is quite good, yet its bottom speed is not high enough for comfortable play at 1280x1024. You need more overclocking for that.