Powerphasing isnt usually something you think about when specing a rig, the exception with particularly high power CPUs. Because fx CPUs were released on a compatible socket to motherboards which were not originally designed to take 8 and 6 core CPUs, it is not surprising that these high powered chips can draw more power than some older boards can handle.
Let me just find something to copy and paste to save some time:
Phases are structures on your motherboard that supply the overall power to your CPU through VRM's and MOSFET's. They are important with supplying your CPU with power, and if one were to die, the entire motherboard would most likely.
Usually common phase designs for amd are:
4+1
4+2
8+2
I think Asrock Fatal1ty offers 12+2 and the Asus Evo i know offers 6+2. The first number means the number of phases that are dedicated to the CPU. This is really the only important number (the second number is the number of phases dedicated to the RAM and HT, which wont pull near the same power). So obviously at first glance, more phases is better, since there are more structures to regulate power and power/heat is spread better. That however is not all, there are heatsinks on the VRMs on most boards, which help prevent them overheating. If they overheat they will either blow and ruin your board and maybe more components or more likely just throttle your CPU speed and voltage.
Different manufacturers use different components when designing their phasing. Different product ranges from the same manufacturer can also use different quality of components, for example, you can bet that the VRMs and MOSFETs which make up the power phase design are of better quality in the Crosshair Formula V board than the lower end Asus M5A78L LE board. Better components mean that they will not throttle till much higher temperatures and are much less likely to blow if they get too hot or there is a sudden surge in power because they are designed to and are capable of delivering higher currents.
In short, more phases are often better because you spread the power through more structures even if the parts used are different (it is cheaper for manufacturers to use sixteen 8A transistors than four 32A). With this in mind, it is important to make sure that the VRM design is from a quality manufacturer. In recent times, specifically more with 8 core FX chips, the brands Asrock and MSI have produced a few boards which have earned a reputation for unreliable phasing at higher voltages.
Dont worry too much if you dont fully understand. unless you plan on breaking world record over clocks, you can get away with the 6+2 phasing on the EVO board and you wont gain benefit from any better phasing unless you were aiming to run it at 1.5V.
