TweakIt extends the functions of the external LCD Poster device. You can use it as a regular POST debug display or you can use it in conjunction with three of the micro buttons to change BIOS settings while Windows is running. The display on the LCD Poster is absolutely tiny and the controls are fiddly when the motherboard is flat on the test bench so the idea of working with TweakIt inside a PC case doesn't bear thinking about.
The other two micro buttons in the array are the usual Power and Reset, and there's a Clear CMOS button on the I/O panel.
The expansion slots centre around three widely spaced PCI Express 2.0 x16 slots. They can be used as dual x16 slots for CrossFire or SLI and if you fancy a spot of Tri-SLI the configuration switches to x16 x8 x8. We used our regular GeForce 8800GT graphics card in testing and saw 14,658 marks in 3DMark06. But, just for the heck of it we plugged in a single GTX 280 which raised the score to 19,020 marks and then added a second GTX 280 in SLI for 23,898 marks - and that's on a Beta graphics driver.
The slot just below the Northbridge is for the exclusive use of the X-Fi audio riser card and there's a single PCI slot that will be blocked if you use a pair of double slot graphics cards. If you fill the Rampage II Extreme with two or three graphics cards you'll run out of expansion options but we don't see that as a problem as the I/O panel is chock full of USB, Firewire and eSATA ports and the ICH10R Southbridge powers six SATA ports with RAID. It's hard to see what else Asus could bring to the party unless you have a penchant for Serial or Parallel ports.
It's still early days for Core i7 so we are taking it very easy with the power settings when it comes to overclocking. We ran our Core i7 965 Extreme at the stock 3.2GHz setting and then used the Asus CPU Level Up feature set to i7-crazy-3.60G or i7-crazy-4.00G which changes the memory speed to 1202MHz and 926MHz respectively.