About

A stable power supply is the backbone of any computer system. Undersized PSUs cause random shutdowns, system instability, and potential hardware damage, while vastly oversized units are inefficient and expensive. This calculator aggregates the Thermal Design Power (TDP) of every component in your rig, from the latest high-performance GPUs to storage drives and cooling fans.

We apply a recommended safety overhead factor (typically 20%) to the peak load calculation. This ensures the PSU operates in its peak efficiency curve (usually around 50-70% load) and accommodates transient power spikes, capacitor aging, and future upgradability.

Formulas

The Total System Power P_sys is the summation of all individual component TDPs:

P_sys = P_cpu + P_gpu + P_mobo + n∑i=0P_other

To determine the Recommended PSU Wattage W_rec, a safety buffer k (default 1.2 or 1.5) is applied to ensure longevity:

W_rec = P_sys × 1.2 + 50

(50W constant is added for USB peripherals and uncalculated capacitors).

Reference Data

Component	Avg. Power (Idle)	Avg. Power (Load)	Notes
High-End GPU	15 W	300-450 W	Major power consumer
Mid-Range CPU	10 W	65-125 W	Varies by overclocking
Motherboard	25 W	50 W	VRM losses included
RAM (per stick)	2 W	5 W	DDR4/DDR5
SSD (NVMe)	1 W	8 W	Efficient
HDD (7200rpm)	5 W	20 W	Spin-up current high
Case Fans	1 W	3 W	Per 120mm fan

Frequently Asked Questions

If the PSU cannot supply the required power, the system will likely shut down abruptly during heavy tasks (like gaming) to protect itself (OCP - Over Current Protection). Repeated triggering can damage storage drives or corrupt OS files.

No. A PSU only draws what the components need. A 1000W unit powering a 300W PC will only draw approx. 330W from the wall (accounting for efficiency loss). However, higher wattage units are often more expensive.

Peak is the absolute maximum the parts might draw in a stress test. Recommended includes headroom. PSUs run most efficiently, quietly, and coolly at 50-60% of their maximum capacity, not 100%.

Yes, significantly. Overclocking requires increasing voltage, which increases power consumption exponentially, not linearly. If you plan to overclock, add an extra 10-15% margin.