About

Constructing a custom desktop requires precise engineering to avoid thermal throttling, power instability, or hardware incompatibility. A mismatch between the Central Processing Unit and the Graphics Processing Unit often results in wasted potential, known as a bottleneck. Additionally, underestimating the power draw of transient spikes leads to system instability or shutdown. This tool models the electrical and data throughput characteristics of hardware components. It aggregates Thermal Design Power values to recommend a Power Supply Unit with sufficient overhead for capacitor aging and efficiency curves. Users simulate configurations to verify socket matching, physical clearance, and performance balance before investing in physical hardware.

Formulas

The system stability relies on calculating the Total System Power P_sys and ensuring the Power Supply Unit P_psu offers adequate headroom. The recommended wattage incorporates a safety factor σ for capacitor aging and transient spikes.

1. Total TDP Calculation:

P_sys = n∑i=1 TDP_i + P_overhead

2. Recommended PSU Wattage:

P_rec = {

P_sys × 1.20 if P_sys < 500P_sys × 1.25 if P_sys ≥ 500

3. Bottleneck Index (B):

B = Score(GPU)Score(CPU) × R_factor

Reference Data

Component Tier	Typical TDP (W)	Rec. Headroom (%)	1080p Bottleneck Risk	4K Bottleneck Risk
Entry Level (i3/Ryzen 3 + xx60)	250 - 350	20	Low	High (GPU Bound)
Mid-Range (i5/Ryzen 5 + xx70)	350 - 500	20	Moderate	Moderate
High-End (i7/Ryzen 7 + xx80)	500 - 750	25	High (CPU Bound)	Low
Enthusiast (i9/Ryzen 9 + xx90)	750 - 1000+	30	Very High	Low
Workstation (Threadripper)	1000+	30	Low	Low
Server / Dual Socket	1500+	35	N/A	N/A
Mini-ITX SFF Builds	200 - 400	15	Moderate	High
Liquid Cooled Custom Loop	600 - 900	25	Low	Low

Frequently Asked Questions

TDP (Thermal Design Power) represents heat dissipation, not peak electrical draw. Modern GPUs experience transient spikes lasting milliseconds that can exceed their rated TDP by 2x. A 20-30% overhead buffers these spikes and keeps the PSU operating in its most efficient range (typically 50-70% load).

At lower resolutions like 1080p, the GPU processes frames faster than the CPU can prepare them, making the CPU the limiting factor. At 4K, the GPU load increases massive, shifting the bottleneck to the graphics card. A balanced build depends heavily on the target monitor resolution.

The system will not assemble physically or electrically. DDR4 and DDR5 DIMM slots have different key notches to prevent incorrect insertion. This tool checks the chipset and motherboard specifications to flag memory generation incompatibility immediately.

While the tool calculates power and electronic compatibility, physical constraints like GPU length versus Case maximum video card clearance, or CPU cooler height versus Case width, should be verified against the chassis manufacturer's specific manual.

High-end GPUs (RTX 40-series) utilize the 12VHPWR connector which can deliver up to 600W through a single cable. Using a native ATX 3.0 PSU is safer and cleaner than using multiple 8-pin adapters, reducing resistance and fire risk.