PSU Calculator
Calculate exact power supply wattage for your PC • Real-time recommendations
1 Select Your CPU
2 Select Your GPU
3 Memory & Motherboard
4 Storage Drives
5 Cooling & Accessories
PSUs operate most efficiently at 50-80% load. Extra headroom accounts for component aging, future upgrades, and ensures stable power delivery during transient spikes from your CPU and GPU.
Frequently Asked Questions
How much PSU wattage do I need for gaming?
Most gaming PCs need 550-750W. A mid-range build with RTX 4060 or RTX 4070 typically needs 550-650W, while high-end builds with RTX 4080 or RTX 5090 require 750-1000W. Always add 20% headroom above your calculated wattage for efficiency and future upgrades.
What PSU do I need for RTX 4090 or RTX 5090?
For an RTX 4090 (450W TDP), we recommend at least 850W, ideally 1000W. For the RTX 5090 (575W TDP), you need minimum 1000W, ideally 1200W. Both cards have significant power spikes, so ATX 3.0 compliant PSUs with native 12VHPWR connectors are strongly recommended.
Is 650W PSU enough for RTX 4070?
Yes, 650W is typically sufficient for an RTX 4070 (200W TDP) paired with most mainstream CPUs like Ryzen 5 7600X or i5-14600K. However, if you have a power-hungry CPU like i9-14900K or plan to overclock, consider 750W for extra headroom.
What PSU efficiency rating should I get?
80 Plus Gold is the sweet spot for most users, offering 87-90% efficiency at typical loads. Bronze is acceptable for budget builds. Platinum and Titanium provide marginal efficiency gains at higher cost. Higher efficiency means less heat, lower electricity bills, and often better component quality.
Do I need to account for power spikes?
Yes, modern GPUs like RTX 4090 and RTX 5090 can spike 200-300W above their rated TDP for microseconds. Quality PSUs handle these transients, but budget units may shut down or trip over-current protection. Our calculator automatically adds appropriate headroom for power spikes.
Should I get a modular PSU?
Fully modular PSUs let you use only needed cables, improving airflow and aesthetics. Semi-modular offers good value with fixed 24-pin/CPU cables. Non-modular is fine for budget builds where cable management isn't a priority.
Can my PSU be too powerful?
A PSU cannot be "too powerful" – it only delivers what your system needs. However, PSUs operate most efficiently at 50-80% load. A 1000W PSU running a 300W system operates at 30% load, slightly reducing efficiency. Match your PSU to your needs with room for upgrades.
Complete Guide to Choosing a Power Supply
Understanding PSU Wattage
Your PSU's wattage rating indicates the maximum power it can deliver. However, for optimal efficiency and longevity, you should operate at 50-80% of rated capacity. A 750W PSU running a 400W system operates at ~53% load – the efficiency sweet spot.
Calculate your total system power by adding all components: CPU TDP (65-170W), GPU TDP (75-575W), RAM (~5W per stick), storage (3-10W per drive), motherboard (50-80W), and cooling. Then add 20% headroom for efficiency, transients, and future upgrades.
PSU Recommendations by Build Type
| Build Type | Example GPU | Minimum PSU | Recommended |
|---|---|---|---|
| Budget Gaming | RTX 4060, RX 7600 | 500W | 550-650W |
| Mid-Range Gaming | RTX 4070, RX 7800 XT | 600W | 650-750W |
| High-End Gaming | RTX 4080, RTX 5080 | 750W | 850W |
| Enthusiast/Extreme | RTX 4090, RTX 5090 | 850W | 1000-1200W |
| Workstation/Multi-GPU | Multiple GPUs | 1000W | 1200-1600W |
80 Plus Efficiency Ratings Explained
The 80 Plus certification indicates minimum efficiency levels at 20%, 50%, and 100% load:
- 80 Plus White: 80% efficiency – Budget builds only
- 80 Plus Bronze: 82-85% efficiency – Good budget choice
- 80 Plus Gold: 87-90% efficiency – Best value for most users
- 80 Plus Platinum: 89-92% efficiency – Premium builds
- 80 Plus Titanium: 90-94% efficiency – Maximum efficiency, highest cost
Key Features to Look For
- ATX 3.0 / PCIe 5.0 Compliance: Required for RTX 40/50 series with native 12VHPWR connector
- Japanese Capacitors: Better reliability and lifespan than cheaper alternatives
- Modular Cables: Easier cable management and cleaner builds
- Zero RPM Fan Mode: Silent operation at low loads
- Warranty Length: 7-10 years indicates quality confidence
- Protection Features: OVP, OCP, SCP, OTP for system safety