Unreal Tournament 3 only stressed a single core heavily, while a second core worked at around 50%. This put the Phenom II X6 1090T at a disadvantage remaining slower than the Core i5 750.
Company of Heroes: Opposing Fronts stressed a single single core further confirming that this game is showing its age. Despite the apparent lack of multi-threading support, the Phenom II X6 processors provided tangible gains against the Phenom II X4 965, particularly the 1090T.
Far Cry 2 is one of the better examples of a game optimized for multi-core processors. Having said that we see that only one core is heavily utilized, two more cores are working at over half their capacity, while the other three are doing almost nothing. As a result the performance of the Phenom II X6 processors is only comparable to that of the Phenom II X4 965.
Resident Evil 5 is the only game we tested that makes use of all six cores. When using the Phenom II X6 CPUs most cores were only used at ~50% of their capacity for an overall utilization level of around 60%. This had the processors showing a slight performance advantage over its quad-core sibling, but it wasn't enough to beat the Core i5 750.