What limits the CPU power on a motherboard



New Member
What limits the CPU power on a motherboard. Some have limits, like 95watts, but can be overclocked. Does the BIOS or CMOS limit it. Can the limit be changed. How does the motherboard know.


Active Member
The TDP (Thermal Design Power, ex: the 95 watts you mentioned) is not really a limit, but more of a guideline so motherboard and OEM system builders can determine where a CPU can be used and how to spec other parameters around it (power delivery, cooling, case size, etc.)

The TDP is rated for stock speeds, but if the CPU is unlocked and can be overclocked it does not limit you to its TDP value. However, when going above TDP you have to make sure the rest of your system (motherboard power delivery, power supply, case and CPU cooling) are up to the task for the increased load.

Cheaper motherboards and parts might not cope well with the increased power consumption, that's why for example the AMD FX-9xxx series with their 220W TDP cannot be used with many motherboards as most of them are built with a 140W TDP in mind (plus some margin for overclocking). Some motherboards have BIOS settings to constrain power delivery, but it's usually not necessary as the boards not designed to be ran above TDP usually do not support overclocking in the first place. That's also why overclocking motherboards have overbuilt power circuitry.