The AMD Phenom II X4 955 gets a 2fps performance boost in Unreal Tournament 3 when using DDR3 memory, making it 8fps faster than the Phenom II X4 940, and 10fps slower than the Intel Core 2 Quad Q9650.
The Crysis Warhead results are interesting as the game does not appear to be quad-core optimized, while the developers claim it to be. The Core 2 Quad Q9650 and Core 2 Duo E8600 processors for example both averaged 100fps. Furthermore, the Core 2 Duo E6700 was 5fps faster than the Phenom X4 9950. The Phenom II X4 955 managed 95fps, making it 5fps slower than the Core 2 Quad Q9650 and Core 2 Duo E8600 processors.
The AMD Phenom II X4 955 turns in its best low quality gaming result in Far Cry 2, where it was 3fps faster than the Core 2 Quad Q9650 and Phenom II X4 940 processors. This game appears to be rather well optimized for quad-core processing units.