Voltage and the Current draw at that Voltage and the ability to dissipate the heat.. You pretty much determine the voltage if you alter it from the BIOS determined value (Based on CPU)
So the varable is current. The current is based on several varaibles. (1) work down by the CPU based on what you + background programs are doing (Can Find % of CPU utilization. The freq used by the CPU ( stock vs OCed). Think of the CPU as a RCL circuit (RCL = Risistance, capacitance, inductive) When Freq goes up R - no effect, Xc (AC Resistance of a capacitor) goes Down, Xl (AC Resistance of an inductor) goes up. The bottom line here is that as Freq goes up the CPU Impeadeance (Fancy name for AC resistance) goes Down = Higher Current. The Temp also has an effect. IF Modern CPUs did not shut down above a given temp a condition called thermal runaway could occur. Semiconductors have a negative temp coeffient (As Temp goes Up R goes down). This means thas as the temp hits a given point the resistance goes down, so Current goes up causing MORE heat, R goes down more, I goes up more untill it goes POOF and gives that burning oder.
Power = Current x Voltag and Voltage = Current / Resistance
Best answer selected by Slipperss.
nAlso another question, my CPU mhz is going up and down, depending on the load. How do i make it constant?
nYou should let to change speeds, when your cpu isnt loaded it drops to a slower speed ans saves power, produced less heat, when more power is needed it goes back to full speed, you wont see any performance impact.