| Component | Typical Idle | Typical Load | Peak Transient | Notes | |-----------|-------------|--------------|----------------|-------| | | 35W | 250W (PL2) | 350W+ | PL2 is 253W, but boards often ignore it. | | AMD Ryzen 9 7950X | 40W | 200W (PPT) | 250W | Efficient architecture, but boosts aggressively. | | NVIDIA RTX 4090 | 50W | 450W | 660W (0.1ms) | Critical: Transient spikes up to 2x average load. | | AMD Radeon 7900 XTX | 45W | 355W | 550W | Better transient control than Ampere, but still spiky. | | DDR5 RAM (2x16GB) | 3W | 10W | 12W | Per module. Higher speeds (6000+) increase draw. | | NVMe SSD (PCIe 5.0) | 0.5W | 11W | 14W | Heatsinks mandatory; 4.0 drives are ~7W. | | Fans (per 120mm) | 0.5W | 2W | 3W | RGB adds ~1W per fan. | | AIO Pump | 3W | 6W | 10W | D5 pumps in custom loops: 20-40W. |
PSU Wattage = (CPU Peak Power + GPU Peak Power) * 1.25 + 50W (rest of system) Then add transient buffer: If GPU has known spikes >2x, add another 200W.
A GPU doesn’t draw constant power. When a shader workload kicks in, current demand changes from 100W to 500W in microseconds . The PSU’s control loop must adjust voltage regulation faster than the load changes. If it can’t, voltage dips below spec (e.g., +12V drops to 11.2V), triggering the GPU’s undervoltage protection or causing crashes.