1. Raw GPU speed
Every card has a relative score from 0 to 1000 (RTX 5090 = 1000), based on public review averages. A preset has a render load. Raw frame rate is:
gpuFps = score × 0.36 ÷ (presetLoad × (resolution ÷ presetResolution)^1.9)
2. VRAM overflow
If the preset wants more video memory than the card has, textures spill into system RAM across the PCIe bus.
overflow = (presetVRAM − cardVRAM) ÷ presetVRAM
gpuFps ×= 1 − min(0.7, overflow × 1.6)
3. RAM pressure
Presets need roughly 6GB (1080p Low), 10GB (1080p Ultra), 13GB (1440p Ultra) and 18GB (4K Max). The operating system takes about 3.5GB. What is missing becomes streaming pressure.
lack = max(0, presetRAM − (capacity − 3.5)) ÷ presetRAM
pressure = min(1, lack × 1.8 + overflow × 0.6)
Pressure raises the stutter rate (about 0.25 to 2.9 events per second), lengthens each freeze from 80 ms up to 250 ms, softens textures, and trims the frame rate by up to 35%.
4. Memory speed
Each memory type has a speed factor (DDR3-1600 = 0.72, DDR5-6000 = 1.00, DDR5-7200+ = 1.04). It sets a frame ceiling and the random frametime jitter, which is what drags 1% lows down.
ceiling = 330 × factor² × (1 − 0.3 × pressure)
jitter = 0.03 + (1.04 − factor) × 0.18
fps = (gpuFps⁻⁴ + ceiling⁻⁴)^(−¼)
5. Memory kits and the catalog
Each kit's speed factor comes from a curve fitted per memory family (DDR2, DDR3, DDR4, DDR5) against its data rate in MT/s. First-word latency (CL × 2000 ÷ MT/s) then nudges the factor by up to ±3% against a typical kit of the same family. Total capacity feeds the RAM-pressure model above. The catalog lists typical configurations of real product lines; exact part numbers should be confirmed with the maker.
6. Benchmarks and the upgrade advisor
The 30-second benchmark runs the same frame sampler as the live view without drawing anything, so it finishes instantly. The planner's upgrade advisor re-runs the model with more RAM, faster memory or a stronger GPU and ranks the estimated FPS gain and stutter reduction.
7. Frame pacing on screen
Each build keeps its own simulated clock. A frame is presented only when that clock reaches the next frame time, so an 18 FPS build really updates 18 times a second. Stutters push the next frame back by 80 to 250 ms. Your display's refresh rate still caps what you can see, but the telemetry (FPS, 1% low, 0.1% low, frametime graph) is computed from the simulated frames, not from your monitor.
8. Resolution and textures
Render resolution sets the size of the internal pixel buffer. At 720p and below the buffer is upscaled with smoothing off, giving hard pixels. Above that it is upscaled with bilinear filtering. Texture loss under RAM pressure is simulated by an extra downscale and upscale pass, with a brief extra blur after each stutter as textures pop back in.
Limits
Real games vary with the engine, driver, CPU and settings. Scores are approximate and some newer cards are projections. Use the numbers to compare builds against each other, not as a promise of what a specific game will do.