Choosing the right Power Supply Unit (PSU) is one of the most critical steps in building a PC. An underpowered PSU can cause system instability and random crashes, while an oversized one can be inefficient.
This calculator makes it easy. Simply select your CPU and GPU from the dropdown lists, and we will estimate the recommended power supply wattage for your build, ensuring your system has the stable power it needs to perform at its best.
Calculate Your Power Supply Needs
Select one CPU and one GPU to get your instant recommendation.
3 Add Other Components
Understanding the Results: Wattage and Headroom
The wattage number you see is our recommendation for the minimum continuous power your PSU should supply. This result is calculated by adding the maximum power draw (TDP) of your selected CPU and GPU, plus the power needed for your other components, and then adding a crucial safety buffer.
This “headroom” is vital for two reasons:
- System Stability: It ensures your PSU can handle sudden spikes in power demand during intensive tasks like gaming or rendering without shutting down.
- Future-Proofing: It gives you the flexibility to upgrade components in the future without needing to immediately buy a new power supply.
Internal Link: Before finalizing your PSU, make sure you’ve chosen the right core components. Compare the latest models with our CPU Comparison Tool and GPU Comparison Tool to find the perfect match for your build.
Beyond Wattage: 3 Key Factors in Choosing a PSU
Wattage is just the starting point. To make a truly informed decision, consider these three critical factors:
1. Efficiency Rating (80 Plus Certification)
A PSU’s efficiency rating tells you how effectively it converts AC power from your wall outlet into DC power for your PC components. During this conversion, some energy is always lost as heat. A more efficient PSU wastes less energy, which translates to lower electricity bills, less heat, and often quieter operation.
The industry standard for efficiency is the 80 Plus certification, which guarantees at least 80% efficiency at various load levels. The certification has several tiers:
- 80 Plus Bronze: A great starting point for budget to mid-range builds.
- 80 Plus Gold: The sweet spot for most gamers and content creators, offering excellent efficiency without a huge price premium.
- 80 Plus Platinum & Titanium: Top-tier efficiency for enthusiast builds and workstations that run under heavy load for extended periods.
External Link: A higher rating almost always indicates higher quality internal components and better reliability. To learn more about the specific requirements for each tier, see the official 80 Plus certification standards.
2. Modularity: Tidy Cables, Better Airflow
PSU cables can be a major source of clutter inside a PC case. Modularity refers to whether the cables are permanently attached or detachable.
- Non-Modular: All cables are permanently attached to the PSU. It’s the most budget-friendly option, but cable management can be difficult.
- Semi-Modular: The essential motherboard and CPU cables are attached, while optional cables (for GPU, SATA, etc.) are detachable. This offers a good balance of convenience and price.
- Fully-Modular: Every single cable is detachable. This provides the cleanest look and easiest building experience, as you only need to plug in the cables your system requires.
3. Form Factor: Does it Fit Your Case?
PSUs come in different physical sizes, known as form factors. The vast majority of desktop PC cases use the standard ATX form factor. However, if you are building in a smaller case (Mini-ITX or Micro-ATX), you may need a more compact SFX power supply. Always check your case specifications to ensure compatibility before buying a PSU.
Frequently Asked Questions (FAQ)
Do I need more wattage for overclocking?
Yes. Overclocking your CPU or GPU increases their power consumption. If you plan to overclock, it’s wise to add an extra 100-150 watts to your calculated requirement to ensure stability.
What is a PSU Tier List?
A PSU tier list is a community-driven resource that ranks power supply models based on performance, reliability, and the quality of their internal components, going beyond just the efficiency rating. They are an excellent tool for verifying the quality of a specific model before you buy.
What are the best PSU brands?
While model quality is more important than brand alone, some of the most reputable and trusted brands in the market include Seasonic, Corsair, be quiet!, Cooler Master, Super Flower, and EVGA.
Is it okay to buy a cheap, uncertified power supply?
No. The PSU is the one component you should never cheap out on. A low-quality power supply can be inefficient, unreliable, and in the worst-case scenario, it can fail and damage other expensive components in your PC. Always choose a unit from a reputable brand with at least an 80 Plus Bronze certification.