The BIOS of ASUS Maximus Extreme mainboard is based on AMI micro-code. The first page looks very common and standard, but the second one demonstrates all the goodies this board has to offer. However, you will not see the entire set of Extreme Tweaker options right away. Here is what you get at first:
CPU Level UP parameter allows pushing the processor overclocking to the desired level. The available list may vary depending on the CPU you’ve got.
Memory Level Up parameter works in a similar way, although there are fewer options available here.
Among the options within Ai Overclock Tuner you can now see new technology called X.M.P. (Extended Memory Profiles). The memory modules SPD may contain info on their overclocking friendly features, so by selecting this item from the menu you will ensure that the memory will be set up in accordance with the overclocking parameters from the SPD.
If we decide to adjust I Overclock Tuner manually, we will be able to change the FSB frequency from 200MHz to 800MHz and PCI-E frequency from 100MHz to 150MHz. However, the memory frequency adjustment turns a bit tricky. The list of available parameters is pretty long, but the very last two marked with "*" are not available in the manual mode.
The thing is that when you set the memory frequency at 1600MHz or 1800MHz, the appropriate FSB frequency and processor clock multiplier are automatically selected, which is reported in the informational window on the right.
For example, when we select DDR3-1600MHz and use a CPU with 2.66GHz (266x10) frequency, the FSB gets increased to 400MHz and the multiplier reduces to 7. As a result, the processor frequency increased insignificantly and equaled 2.8GHz (400x7), however the memory worked at 800 (1600) MHz as was promised right from the start.