We started testing the Maximus with a dual-core E6750 so we could run the OCZ PC3-1600 that we reviewed here at full speed on an X38 chipset. And very nice it was too.
Then we plugged in a Core 2 Extreme QX6850 and CPU performance dropped through the floor so we updated to the latest Beta BIOS version 0403 and performance was restored.
However, we noticed that a few options had changed. With the original BIOS version 0301 the list of memory speeds included 1600 and 1800 and a third option labelled *1,800*, which is meant to optimise the CPU and memory speeds. Instead it caused the system to restart which is just what we found when we tried to use a pre-programmed BIOS profile for the QX6850 with the Maximus Formula SE.
The new BIOS changed the memory speed options so the fastest regular speed was 1,333MHz followed by 1,600MHz and 1,800MHz. However, these speeds are only available when you use the standard front-side bus speed. This seems perverse as any Core 2 processor will overclock a treat and will respond to a faster front-side bus, while more memory speed adds relatively little extra performance.
Of course, this may change again in future BIOS updates but for the time being we forgot about the automatic overclocking profiles and the associated pleasures of the Crazy system and its LEDs. Instead, we cranked up the front-side bus from 333MHz to 380MHz to give a clock speed of 3.42GHz. Our QX6850 would hit 400MHz for a speed of 3.60GHz but was unstable in CrossFire, which would rather seem to miss the point with this motherboard. The memory options limited the speed to 1,521MHz but even so the performance was excellent.
You pay plenty for the Maximus Extreme, but that's true of any X38 motherboard. We're not convinced about the merits of three graphics slots but neither can we see any harm in the set-up that Asus has chosen and the cooling system and Fusion block are simply superb.