v3.4 - GPU OC Voltage Sweep Complete
GPU OC 600 MHz - Voltage Sweep Complete
Full undervolt testing of the GPU OC 600 MHz feature across the entire stable range.
What's new
GPU OC voltage menu now covers the full range from 1150 mV down to 1025 mV.
Start at 1150 mV (safe) and reduce gradually. Test each step with a sustained GPU workload and visual inspection. Results depend on your specific chip - silicon lottery applies.
Reference data (one L2 bin chip)
Results below are from a single device (L2 bin, pvtm-volt-sel=2). Your chip may be more or less tolerant.
| Voltage | FPS (on-screen) | Artifacts | Result |
|---|---|---|---|
| 1150 mV | 15 | No | Stable |
| 1112.5 mV | 15 | No | Stable |
| 1087.5 mV | 15 | No | Stable |
| 1062.5 mV | 15 | No | Stable |
| 1037.5 mV | 15 | No | Stable |
| 1025 mV | 15 | No | Stable (this chip) |
| 1012.5 mV | 13 | Yes | Artifacts (this chip) |
Total undervolt on this chip: -125 mV from PMIC max (1150 mV to 1025 mV).
Key findings
- GPU OC has much more undervolt headroom than stock GPU UV (which was limited to -12.5 mV at 520 MHz)
- Root cause: the 600 MHz OPP is a separate node - patching its voltage does NOT affect the 400/480/520 MHz OPPs. The old stock UV limit was caused by the 400 MHz OPP approaching the PMIC floor (950 mV).
- Crash behavior at too-low voltages: device boots normally (GPU stays at low freq during boot), artifacts/crash appear only when devfreq scales GPU to 600 MHz under load. Safety service does NOT trigger in this case.
Full research data
See docs/opp-research.md for complete OPP tables, sweep methodology, and crash behavior analysis.
Tested on R36S / RK3326 / L2 silicon bin / dArkOSRE-R36