Will the radiation increase when the CPU of an edge box is running at full load?

When the CPU of an edge computing box is running at full load, the core frequency switches more frequently, increasing the switching current of internal logic gates, which leads to an increase in dV/dt and di/dt. Power supply ripple and clock harmonics are consequently amplified. A measured radiated emission margin of a certain edge computing box CPU was 6dB under no-load conditions, but under full load, integer operations at the same frequency point increased by 4-8dB, exceeding the standard by 2dB. Countermeasures:

1. Improve the high-frequency characteristics of the power supply decoupling capacitors by using parallel 0.1μF + 1μF MLCCs.

2. Isolate noise by connecting a PBZ1608E600Z0T ferrite bead in series with the CPU core power supply.

3. Reduce the CPU drive intensity; set the IO drive to a low setting without affecting performance.

4. If the heatsink is metal, it must be grounded; otherwise, it becomes a radiating antenna.

After these optimizations, the radiated emission under full load drops back to the no-load level.