Halo

The differences between the motherboards are more pronounced in Halo. Taking the crown is the Soltek K890Pro-939. Next in line, about 6 FPS behind, are the DFI boards. Bringing up the rear are the Gigabyte boards, about 9 FPS behind. Unfortunately, the K8N Ultra-SLI takes the last spot.
Half-Life 2

Sadly, the two Gigabyte boards bring up the rear once again, but this time the K8N Ultra-SLI overtakes the K8NXP-SLI by about 2 FPS. The difference between the highest and lowest scores is 5 FPS which is a delta of 8%, which is not insignificant.