About PSUCheck
PSUCheck exists because PC builders deserve better tools. Every PSU calculator we found was either built by a manufacturer recommending only their own products, or was a shallow wattage sum with no real engineering depth. We built the tool we wished existed.
What PSUCheck Is
PSUCheck is a free, independent web application that helps PC builders accurately calculate power supply requirements, estimate total build cost, and understand the real engineering behind modern PC power delivery.
Unlike manufacturer tools (Seasonic, Corsair, be quiet!, ASUS, Cooler Master) that are structurally limited to recommending only their own products, PSUCheck is brand-agnostic. We recommend whatever PSU best fits your build — regardless of who makes it.
What PSUCheck Is Not
PSUCheck is not a retailer, manufacturer, or affiliated with any hardware company. We do not receive payment from hardware brands for recommendations. Affiliate commissions (from Amazon and Newegg links) are based solely on user purchases — not on which brands we feature or how prominently.
PSUCheck does not collect personally identifiable information. Calculator results are computed client-side in your browser. We do not store your build configurations.
Our Methodology
Every calculation in PSUCheck is based on published, verifiable data sources. We do not fabricate wattage figures, invent transient multipliers, or guess at hardware specs. If a data point is uncertain, we flag it explicitly.
⚡ Transient Multipliers
GPU and CPU transient scaling factors sourced from Cybenetics PSU Lab published methodology. GPU tier multipliers: 1.20× (budget) to 1.57× (halo-class RTX 5090).
🔌 ATX 3.1 Spec
ATX 3.1 transient tolerance (200% of rated output for 100μs) sourced from the Intel ATX 3.1 Design Guide (2024 revision).
🎮 GPU Power Data
GPU Total Board Power (TBP) from NVIDIA/AMD official product pages and cross-referenced against TechPowerUp GPU database.
🖥️ CPU Power Data
Intel CPUs use PL2 (Maximum Turbo Power) from Intel ARK. AMD CPUs use TDP from AMD official specifications.
📊 Efficiency Curves
80 PLUS efficiency curves (Bronze through Titanium at 10/20/50/100% load) from CLEAResult 80 PLUS certification program public data.
💰 Component Pricing
Retail prices compiled from manufacturer suggested retail prices (MSRP) and current US retailer listings. Updated quarterly. Prices are estimates and may vary.
Full methodology documentation: psucheck.com/methodology
Sizing & Sizer Calculations Methodology
PSUCheck uses a rigorous mathematical model derived from Intel's ATX 3.1 specification, Cybenetics Lab load metrics, and real-world reviewer oscilloscope testing. Here is exactly how our sizer calculates your system's power footprint:
1. Sustained Base Power Draw
We calculate the continuous operating load by summing the sustained thermal design power (TDP) or total board power (TBP) of your components plus baseline infrastructure overheads:
BaseDraw = CPU_TDP + GPU_TBP + RAM (10W) + NVMe (10W) + Cooling (10W) + Fans (12W) + System Overhead (15W)2. Transient Peak Power Excursions
Modern processors and graphics cards pull short microsecond-level power spikes (transients). We model this peak draw by applying GPU-tier multipliers (ranging from 1.2× to 1.7× based on Cybenetics benchmarks) and CPU transient factors:
TransientPeak = (CPU_TDP × 1.20) + (GPU_TBP × GPU_Transient_Multiplier) + 32W (System Transient Overhead)3. Recommended PSU Sizing
To find the safe PSU wattage, we apply a headroom multiplier based on the ATX specification. ATX 3.0/3.1 systems natively handle up to 200% transient spikes, allowing a tighter 20% buffer. Legacy ATX 2.x systems require a 35% buffer to prevent OCP trips:
- ATX 3.0 / 3.1: Recommended = TransientPeak × 1.20 × (1 + SafetyBuffer/2)
- ATX 2.x: Recommended = TransientPeak × 1.35 × (1 + SafetyBuffer/2)
We then factor in **capacitor aging degradation** (increasing required wattage by 5% annually starting at year 4) and round up to the nearest standard output tier (e.g. 550W, 650W, 750W, 850W, 1000W, 1200W, 1600W).
4. PSU Health Scoring
Our PSU Replacement Calculator grades power supply units out of 100 using a composite index:
- Age Weight (50%): 100% capacity for years 0-3, then drops 5% annually.
- Headroom Weight (25%): Evaluates the difference between effective capacity and transient peak draw.
- Transient Safety Weight (15%): Confirms if effective capacity stays above transient spikes.
- Connector Weight (10%): Grades native 12V-2x6 / 12VHPWR links (100) vs daisy-chain configurations (30-70).
Known Limitations
- Transient measurements are tier-based estimates. Per-SKU sub-millisecond oscilloscope measurements are not publicly available for all GPUs. We use Cybenetics' published tier multipliers, the same methodology used by TechSearchers.
- Pricing is approximate. Component prices fluctuate daily. Our database is updated quarterly. Always verify current pricing before purchasing.
- Unconfirmed hardware is flagged. Leaked or rumored GPU/CPU specs (e.g., RTX 5080 SUPER) are explicitly labeled "⚠ Estimated — Not Yet Confirmed by Manufacturer."
Questions or Corrections?
If you find an error in our data, a stale price, or a missing component, please let us know. We're committed to accuracy.
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