Far Cry 2
Despite the good average performance, the bottom speed of the Radeon HD 4670 CrossFireX is not high enough for playing this game at resolutions higher than 1280x1024. Yes, the tandem is head above the mainstream graphics cards but is no match to the performance-mainstream products.
In other words, you won’t be able to play Far Cry 2 at high resolutions if you add a second Radeon HD 4670 to the one you already own. On the other hand, such an upgrade is still more appealing than replacing your Radeon HD 4670 with a Radeon HD 4850 because the latter has problems with bottom speed even at 1280x1024.
Far Cry 2 is the only game in which we had some problems with the smoothness of control. The game seemed to react more slowly to mouse movements, yet not to the extent of total unplayability as had been the case with the Radeon HD 4830 CrossFireX.
F.E.A.R.: Project Origin
Nvidia’s GPUs feel better in this game, delivering higher bottom speeds, so it is no wonder that the Radeon HD 4670 CrossFireX is unable to beat the GeForce 9800 GTX+. Of course, installing a second 4670 allows playing at 1680x1050 but you can achieve the same with a single Radeon HD 4850.
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.
The Radeon HD 4670 pair turns in a splendid performance in Left 4 Dead, being ahead of the GeForce GTX 260 Core 216 at 1280x1024 and only 3-4% behind the latter in the higher display modes. It cannot catch up with the Radeon HD 4870 1GB, but that’s not a problem since its average frame rate is over 60fps even at 1920x1200.
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 enabled the DirectX 10.1 mode for the ATI cards.
Things are not so bright for the Radeon HD 4670 CrossFireX tandem in this test. Notwithstanding good scalability, it cannot deliver a playable frame rate even at 1280x1024. The tandem seems to have enough graphics memory, memory bandwidth and computing resources, so we guess the reason is that the 2x8 RBE design is less efficient than the Radeon HD 4850’s 16 RBEs due to CrossFireX overhead or the rendering techniques employed by the game engine.
The problem we observed in our Crisis Management CrossFireX review is not present here. CrossFireX mode is enabled normally, without your having to enter the vid_restart command in the game console. This problem must have been corrected in the new release of the Catalyst driver.