Intel processors use the following voltages (the names below are the official ones):
- VCC: This is the main CPU voltage, which can also be unofficially referred as Vcore. Usually, when we say “CPU voltage” we are talking about this voltage. The option that changes this voltage will show up on the motherboard setup as “CPU Voltage,” “CPU Core,” etc.
- VTT: This is the voltage rail that feeds the integrated memory controller (on CPUs that have this component), the QPI bus (on CPUs that have this component), the FSB termination (on CPUs that are based on this architecture), the L3 memory cache (on CPUs that have this feature), the thermal control bus (PECI, Platform Environmental Control Interface, on CPUs that have this feature, except from second-generation Core i processors on, where this bus is fed by the VCCIO voltage) and other circuits, depending on the CPU. It is important to understand that on AMD CPUs, “VTT” is the name of a different voltage; the VTT on Intel CPUs is the equivalent of the VDDNB from AMD CPUs. This voltage can be changed through options such as “CPU VTT,” “CPU FSB,” “IMC Voltage,” and “QPI/VTT Voltage.”
- VCCSA: Starting with the second-generation Core i processors (“Sandy Bridge”), the VTT voltage was renamed to VCCSA, and is called “system agent.” It feeds the integrated PCI Express controller, memory controller, and display engine (i.e., the “2D” part of the graphics engine).
- VCCIO: Available starting with the second-generation Core i CPUs (“Sandy Bridge”), this voltage is used for feeding all input/output (I/O) pins of the CPU, except memory-related pins. On CPUs that have this voltage, it is also used to feed the thermal control bus (PECI, Platform Environmental Control Interface).
- VCCPLL: Voltage used by the CPU clock multiplier (PLL, Phase-Locked Loop). This voltage can be changed through an option called “CPU PLL Voltage.”
- VAXG: Voltage used by the video controller embedded inside the CPU, on CPUs that have this component. This option can be called by names such as “Graphics Core,” “GFX Voltage,” “IGP Voltage,” “IGD Voltage,” and “VAXG Voltage.”
- CPU clock voltage: Some motherboards allow you to increase the voltage of the CPU base clock, through options called “CPU Clock Driving Control” or “CPU Amplitude Control.”
Now let’s take a look at the memory options.