hi, I have recently purchased a Z77MX-D3H TH motherboard and I noticed that it has a blue heatsink next to the CPU socket. I know about the chipset heatsink but I have no idea what the heatsink next to the CPU does, im guessing its something to do with over clocking? any help is appreciated, thanks.
It's the MOSFET heatsink.
It is somehow related to OC-ing:
Phase is commonly referenced to as a CPU voltage regulator module. A voltage regulator creates an output voltage requested by the CPU (Usually in the range of 1-2 volts) by converting the +12V power from the system power supply.
These VRM's contain a number of buck converters, each generating the same voltage and a split of the total output current. Each converter usually consists of 2 or 3 switching MOSFET transistors, one coil and at least one capacitor, plus the driver section which can be a separate SMD or included in the main PWM controller. The buck converters do not work simultaneously but alternate with an equal delay between each others switching, this is why the converter is also called "a phase".
There are many advantages for using multiple power phases, the most important being a reduction in required output capacitor size. Each converter "Phase" takes it's turn switching, making the output ripple frequency much higher due to phase interpolation. For example, if we have a converter that works at 500Khz, for a single-phase we would have 500Khz ripple, but for a 4-phase system the ripple would be at 2000khz, this would allow capacitors of 1/4 the size to be used to filter the power. Another advantage of the phase interpolation process is a much faster voltage load response. One advantage is the current distribution, power is drawn from multiple sources lowering current draw on each phase and distributing the heat generated over a larger area. One drawback to multiple phase designs is the increased generation of EMI caused by the very high-frequency ripple, better capacitors such as Japanese solid capacitors are required for output filters. DPWM "Digital Pulse Width Modulation" regulator modules are able to switch at very high frequencies generating very little heat by using extremely efficient ceramic capacitors. http://rog.asus.com/forum/archive/index.php/t-527.html
more about phase: http://www.hardwaresecrets.com/article/Everything-You-N...
Failures on motherboards with higher phase counts have been relatively infrequent if at all. Most of the culprits for VRM failures are the lower end 4+1 phase and 3+1 phase motherboards that aren't equipped to handle processors that consume lots of power and may be overclocked. Smaller 4+1 phase systems or less on CPUs can be particularly risky due to the fact that each transistor must be capable of outputting more current and heat. This is why you normally see motherboards with low phase count failing (i.e. catching fire, frying, overloading), often on motherboards from only certain manufacturers or certain particular motherboards.
However, the motherboard brand/maker and their quality control can also define the quality of a VRM system. For example, the majority of 2010-released MSI AMD motherboards with 4+1 phase or similar, heatsinked or not, did not have good quality and were prone to failure. This was due to the utilisation of transistors that may not be properly rated, driver chips not properly rated, and lack of VRM over-current protection. However, the Biostar TA890FXE, which comes with a similar-sized 4+2 power phase, was not failure-prone. It featured high amperage rating per transistor; completely rock-solid.
An 8+2 phase system may not necessarily provide any more current than a 4+1 phase if the amount of amperge capacity throghout the VRM system is the same; however, the 8+2 phase system would still do so with more efficiency, stability, and with less heat output http://www.overclock.net/t/943109/about-vrms-mosfets-mo...