A mobile SoC rendering AR/VR content generates heat roughly proportional to how much work the GPU does each frame — more on-screen objects (or a higher LOD tier) means more shading and geometry work, and VR effectively doubles the cost by rendering a separate view per eye. The chip's temperature follows Newton's law of cooling:
C · dT/dt = Q_gen(workload, mode) − h·(T − T_ambient)
Q_gen = 0.9 + workload · 0.004 · modeMultiplier (W, model units)
h = cooling efficiency slider (W/°C)
C = thermal mass of the device (J/°C, fixed)
When the die crosses a throttle threshold, the OS applies dynamic voltage/frequency scaling (DVFS): the GPU clock — and therefore the frames the engine can finish per second — is scaled down the hotter it gets, down to a hard floor once it hits the thermal limit:
clockScale = 1 T ≤ T_start (40°C)
clockScale = 1 − 0.65 · (T − T_start)/(T_max − T_start) T_start < T < T_max
clockScale = 0.35 T ≥ T_max (56°C)
FPS = targetFPS(mode) · clockScale
frame time (ms) = 1000 / FPS
- AR vs VR mode — sets the target frame budget (60 FPS for a handheld AR overlay, 90 FPS for a headset) and the heat multiplier (stereo VR rendering runs hotter for the same scene).
- Scene workload — the number of virtual objects the renderer must draw each frame; also drives how many icons float above the device in the 3D view.
- Ambient temperature / cooling efficiency — the two terms of Newton's cooling law that fight the heat the GPU generates.
- The floating AR/VR content visibly stutters once FPS drops — its rotation is only advanced once per simulated frame budget, exactly mirroring how a throttled device renders fewer real updates per second.
- Comfort risk — in VR mode, sustained frame rate below ~85% of the 90 FPS target is a known contributor to simulator/motion sickness because the visual and vestibular systems fall out of sync; the readout escalates the longer FPS stays depressed.
Real-world relevance: this is exactly why ARKit/ARCore and mobile game engines ship a Level-of-Detail budget and a thermal-aware frame pacer — sustained peak GPU load on a phone-sized heatsink throttles within tens of seconds, not minutes.