When using a 4-pin CPU power supply on an 8-pin CPU power connector motherboard, it is possible in some cases but with certain considerations. The 8-pin CPU power connector on the motherboard is designed to provide more power to the CPU, especially for high-performance CPUs that have higher power consumption. The 4-pin CPU power supply can be plugged into the 8-pin connector. However, the motherboard will only receive power from the four pins that are connected. This may be sufficient for some CPUs that don't have extremely high power demands. For example, a mid-range CPU that has a relatively low power draw might work fine with a 4-pin power supply plugged into an 8-pin connector.

But for CPUs that require a full 8-pin power supply or more, using a 4-pin supply could lead to issues. The CPU may not get enough power under heavy load, which could result in system instability, crashes, or even damage to the CPU. It is important to check the power requirements of the CPU. If the CPU is a high-end model that recommends an 8-pin or more power supply, it is advisable to use the appropriate 8-pin or higher power connector. Some motherboards have a design that allows for a 4-pin to be plugged in without major problems, but it still depends on the overall power circuitry and the specific CPU. In general, it is best to match the CPU power supply to the motherboard's requirements to ensure proper operation and avoid potential power-related issues.