[Rovey]

Refs #84. The design #84 asks for, before any code. It is documentation only. Decided by the owner on 2026-11-14, and built for the Undervolt profile in #87 (the implementation PR). Issue #84 stays open.

What it adds

A section in docs/planned.md, Design: a fair before and after (#84):

• What is compared today, with the code it comes from (measure_stock, the undervolt soak, kNotSlowerScore), and the two cases that show the problem: the GTX 1080 Ti of fix: the curve of a GTX 10 card is read in kHz, so its undervolt search can start #83, and the fan control alone moving power and temperature on the reference RTX 4070 (check 76).

• Valid measurements: complete, partial (stopped by the temperature), and a valid comparison (both complete, same fan control). Otherwise there is one not compared: <why> line.

• Comparable sides:

  • the measurement at stock follows the run's fan curve, and is repeated on the moved curve when the ceiling moves it;
  • 300 s on both sides, averaged over the last half.

• The keep/discard rule for the Undervolt profile:

  • not slower than 99 %;
  • no thermal regression;
  • at least one benefit (power, temperature or fans).

  The tolerances are provisional named constants.

• What changes for a cool and a hot card, how it is built, and hardware checks 111 and 112.

Update after review

• The owner's five choices are recorded under "Decided":
  1. stock on the run's curve, with a second measurement on a moved curve;
  2. discard without a valid comparison;
  3. the last 150 s;
  4. provisional named tolerances;
  5. a "Before" heading that names the app's fan curve.
• Two approved deviations:
  • the speed profiles and All in one keep their measurement at stock on the driver's fans;
  • an undervolt on top of a saved tune is not judged against stock.
• Hardware check 111 passed on the reference RTX 4070 (2026-11-14): three runs at the same 990 mV, and twice the scatter of the counted half fits every provisional tolerance (score 0.09 %, power 1.3 %, temperature 2 C, fan 2 points at most). The values stay as they are. Check 112 (a card that is hot at stock) has not run; it needs a tester.

Checked

• Every number quoted is from Fair stock-versus-undervolt comparison and a keep/discard policy #84, fix: the curve of a GTX 10 card is read in kHz, so its undervolt search can start #83, docs/hardware-checks.md (checks 75, 76, 77) and docs/planned.md.
• One file changed, CRLF as the file has it.
• No code here.

Not to be merged before the owner's review.

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