Calculate the exact PSU wattage needed for your PC build. Enter CPU, GPU, RAM, and storage to get a recommended power supply with 30% headroom, annual energy cost, and the number of solar panels needed to power your workstation
Choosing the wrong PSU is one of the most common PC building mistakes. An undersized PSU can cause system instability, sudden shutdowns, and hardware damage during GPU power spikes. An oversized PSU wastes money and runs at reduced efficiency. This calculator helps you find the sweet spot: enough headroom for transient power spikes without paying for capacity you will never use.
The calculator also includes a unique Solar Bridge feature for solar professionals and eco-conscious builders. After calculating your PC's power draw, it tells you exactly how many solar panels and battery storage capacity you need to run the system off-grid or to fully offset its annual grid consumption. This is useful for solar workstation builds, off-grid content creation setups, and clients who want to power their home office with solar.
All efficiency calculations reference the 80 Plus certification tiers (Bronze, Silver, Gold, Platinum, Titanium) so you can choose a PSU that minimizes electricity waste and reduces the wall draw below the nameplate system wattage.
Enter CPU TDP, GPU TDP, RAM count, SSD and HDD count, and fan count for a precise wattage breakdown showing the contribution of each component to total system draw.
Flags when system wattage exceeds ATX 2.0 PSU limits and recommends ATX 3.0 compliance for GPUs with 12VHPWR connectors like the RTX 4080/4090 that can draw 600W+ in transient spikes.
Calculates how many solar panels and kWh of battery storage are needed to fully power the PC off solar, bridging PC building and solar energy planning in one tool.
Before purchasing a PSU for a new build, run every component configuration through this calculator to confirm PSU wattage. Avoid the common mistake of buying a 650W PSU for a build that needs 720W with headroom, requiring a costly return and exchange.
When upgrading a GPU in an existing system, recalculate total system draw. An RTX 3070 at 220W replaced by an RTX 4080 at 320W adds 100W of load. A 650W PSU that was adequate before may be undersized after the upgrade.
Solar professionals designing off-grid workstations or solar-powered home offices use the Solar Bridge output to specify the correct array and battery size for reliably powering high-draw computing workloads without grid connection.
Find your CPU's TDP (Thermal Design Power) on the manufacturer spec sheet or on sites like CPUBenchmark.net. Intel Core i9 chips are typically 125-253W; AMD Ryzen 9 chips are typically 105-170W. Use the actual TDP, not the turbo boost figure, for accurate baseline calculations.
Find your GPU's Total Board Power (TBP) on the manufacturer spec sheet. This is the most important input: RTX 4060 is 115W, RTX 4080 is 320W, RTX 4090 is 450W. The GPU is typically 50-70% of total system draw in gaming or rendering builds.
Input the number of RAM sticks (each approximately 3W), SSDs (approximately 5W each), HDDs (approximately 8W each), and case fans (approximately 3W each). These components contribute 20-60W in a typical build, significant enough to affect PSU tier selection.
Choose your target 80 Plus certification level: Bronze (85% efficient), Silver (88%), Gold (90%), Platinum (92%), or Titanium (94%). Higher efficiency means less heat, lower electricity costs, and a longer PSU lifespan, though Platinum and Titanium carry a price premium.
The calculator outputs the recommended PSU wattage with 30% headroom, actual wall draw from the outlet accounting for efficiency losses, annual electricity cost, and the number of solar panels needed to offset the PC's annual energy consumption.
The PSU calculation follows a five-step process from component wattage through to solar offset sizing. All formulas are based on standard electrical engineering principles and 80 Plus efficiency certification data.
Total_DC = CPU_TDP + GPU_TBP + (RAM_sticks x 3W) + (SSD_count x 5W)
+ (HDD_count x 8W) + (Fan_count x 3W) + Misc_drawPSU_min_W = Total_DC x 1.30
Round up to next standard tier: 450/550/650/750/850/1000/1200/1600WWall_Draw_W = PSU_min_W / PSU_efficiency
Where PSU_efficiency:
Bronze = 0.85
Silver = 0.88
Gold = 0.90
Platinum= 0.92
Titanium= 0.94Daily_kWh = Wall_Draw_W x hours_per_day / 1000
Annual_kWh = Daily_kWh x 365
Annual_Cost = Annual_kWh x electricity_rate_per_kWhSolar_kWh_needed = Annual_kWh
Panel_annual_gen = Panel_W x PSH_per_day x 365 x 0.80 / 1000
Panel_count = CEIL(Solar_kWh_needed / Panel_annual_gen)
Default: 400W panel, 4.5 PSH/day, 80% system efficiency
Worked example: A gaming PC: RTX 4070 GPU (200W TDP), Core i7 CPU (125W TDP), 32GB DDR5 RAM (15W), 2 NVMe SSDs (10W each), 3 case fans (15W total), motherboard (50W). Component total: 425W. Add 20% headroom: 425 × 1.20 = 510W. Select a 550W 80+ Bronze PSU minimum. For efficiency and future upgrades: 650W 80+ Gold. At 50% load (275W), Gold tier = 90% efficiency — saving $12/year vs. Bronze.
Calculations sourced from SurgePV’s PC Power Supply Calculator — surgepv.com/tools/pc-power-supply-calculator/
| PSU Wattage | Typical Use Case | GPU Tier | ATX 3.0 Recommended |
|---|---|---|---|
| 450W | Office / HTPC | Integrated graphics or GT 1030 | No |
| 550W | Basic Gaming | RTX 4060 (115W) / RX 7600 | No |
| 650W | Mid-Range Gaming | RTX 4060 Ti (160W) / RX 7700 XT | No |
| 750W | High-Performance Gaming | RTX 4070 Ti (285W) / RX 7900 GRE | Recommended |
| 850W | Enthusiast Gaming | RTX 4080 (320W) / RX 7900 XT | Required |
| 1000W | High-End Gaming / Creator | RTX 4090 (450W) single GPU | Required |
| 1200W | Extreme / Dual GPU | RTX 4090 + high CPU or SLI | Required |
| 1600W+ | Workstation / Mining | Multi-GPU or high-core server CPU | Required |
PSUs operate most efficiently and reliably at 50-80% of their rated capacity. Running a PSU above 90% rated wattage causes excessive heat, accelerated capacitor degradation, and risk of shutdown during transient power spikes. The 30% headroom keeps the PSU in its optimal efficiency range and provides buffer for GPU power spikes that can be 2-3x the rated TBP in millisecond bursts.
The 80 Plus certification program tests PSUs under standardized loads and certifies that they operate at 80% efficiency or better across load conditions. Tiers are: Standard (80%), Bronze (85%), Silver (88%), Gold (90%), Platinum (92%), and Titanium (94%). A Gold PSU delivering 500W DC draws only 556W AC from the wall, versus 625W AC for an uncertified 80% efficient unit. The difference is 69W of heat and wasted electricity.
NVIDIA recommends a minimum 850W PSU for the RTX 4090. In practice, with a high-TDP CPU (i9-13900K at 253W, for example), total system draw can reach 700-750W, making a 1000W ATX 3.0 PSU the correct choice with 30% headroom. The RTX 4090 uses a 16-pin 12VHPWR connector and can spike to 600W transient, requiring an ATX 3.0 compliant PSU to handle that transient without triggering overcurrent protection.
Fully modular PSUs allow you to connect only the cables you need, improving airflow and cable management. Semi-modular PSUs have fixed cables for the 24-pin ATX and CPU EPS connectors, with modular connectors for GPU and storage. Non-modular PSUs have all cables fixed, which can cause cable clutter. For most builds, semi-modular is the best value balance. Modular is ideal for small form factor cases where cable management is critical.
A quality PSU from a reputable brand (Seasonic, Corsair, EVGA, be quiet!) rated at Gold or higher typically lasts 7-12 years with normal use. Most quality PSUs carry 10-year warranties. The main failure points are capacitors and the fan. PSUs running at 50-80% capacity in a well-ventilated case last significantly longer than those constantly running at 90%+ capacity in hot environments.
ATX 3.0 is the updated power supply standard released in 2022, designed to support modern high-power GPUs. Key differences from ATX 2.0: ATX 3.0 includes native 16-pin 12VHPWR connector support, requires handling transient spikes up to 200% of rated power for 100 microseconds without shutting down, improves transient response speed, and adds stricter efficiency requirements at low loads. For RTX 4080 and above, ATX 3.0 is strongly recommended.
Yes. A typical gaming PC drawing 300-400W from the wall needs approximately 1-2 panels worth of solar generation to offset annual energy consumption (about 1,000-1,500 kWh/year). For a fully off-grid solar workstation running during daylight hours, a 2-3kW solar array with 10-20 kWh of battery storage can reliably power most gaming or content creation setups. The Solar Bridge output in this calculator gives you the starting numbers for that sizing conversation.
Size a UPS (Uninterruptible Power Supply) based on your wall draw in VA (volt-amperes), not watts. Divide watts by 0.8 (power factor) to get VA: a system drawing 500W from the wall needs a 625VA UPS minimum. For 15 minutes of runtime during an outage, multiply VA by 15 minutes, then adjust for battery efficiency (typically 85%). Most manufacturers provide runtime charts for their specific units.
Mining rigs run GPUs at sustained 100% load 24/7, which is far more demanding than gaming. For a 6-GPU mining rig using RTX 3060 Ti cards at 200W each (after undervolting), total GPU draw is 1,200W. Add CPU, motherboard, and fans for approximately 1,400W total. You need a 1,600-2,000W PSU with 80 Plus Gold or Platinum efficiency. Some miners use dual PSUs linked with an add-on controller board to share the load across two units.
Yes significantly. Undervolting reduces a GPU's core voltage below stock settings, reducing power draw by 10-25% while maintaining the same clock speed in most cases. An RTX 4090 undervolted from 450W TBP to 350W reduces system draw by 100W, potentially allowing a 1000W PSU instead of a 1200W unit. Undervolting also reduces heat, noise, and GPU degradation over time. Tools like MSI Afterburner make undervolting accessible for enthusiast users.
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