White 126 vs Black 900
White starts from setup 126 (NQRNKBBR), Black from setup 900 (RBBKQRNN). In the encyclopedia since 2026-11-01: neither side starts better.
|cp| ≤ 5 at 400M · 800M · 1.6B · 4B nodes, two independent engines agree
How to play with different setups
White sets up the pieces by position No. 126, Black by position No. 900, mirrored on their own side; the pawns stand as usual.
Moves as usual: White starts; everything else follows the Chess960 rules.
The two setups
White: setup #126 N Q R N K B B R
King on the e-file, rooks on c, h, queen on the b-file; no bishop starts in a corner; the knights start away from the centre. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 126 gives White +0.27 (Morozov Balance Index, 400M nodes).
Black: setup #900 R B B K Q R N N
King on the d-file, rooks on a, f, queen on the e-file; no bishop starts in a corner; the knights start away from the centre. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 900 gives White +0.17 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±2 centipawns of equality, reaching search depth 57.
Admission rule: |cp| ≤ 5 at four budgets up to 4 billion nodes, no one-sided drift along the ladder, and confirmation by two independent engines — Berserk and Lc0 — each below its own median on symmetric positions. The same corridor is required at every deeper budget (8 G, 16 G) at which the pair has been evaluated.
The shallow rungs wandered between -12 and +20 cp before settling — a reminder that quick engine checks overstate imbalances, and why the ladder goes deep.
For comparison, in symmetric play setup 126 gives White +0.27 and setup 900 gives White +0.17: with both sides on the same rank the first move is worth something. In this pair Black's own setup absorbs that edge completely.
White is not forced into a single path: the best first move is e4, and 2 first moves are within 10 cp of it.
Along the engine's main line (11 moves) the evaluation stayed within ±24 cp the whole way: the balance holds as the pieces come out, not only on move one.
Engine self-play agrees: 10 games, White won 0, drawn 10, Black won 0 (White scored 50.0%).
Verification ladder
Nine independent searches of the starting position, each with a larger node budget. Evaluation in centipawns from White's point of view.
| Stage | Nodes | Depth | Eval, cp | Main line |
|---|---|---|---|---|
| S0 | 100 000 | 14 | +12 | 1. c4 f5 2. f3 Qg6 3. Nc3 Nf6 4. Qc2 c6 |
| S1 | 500 000 | 20 | +4 | 1. c4 f5 2. f3 Qg6 3. Nc3 Nf6 4. Qc2 c6 |
| S2 | 2 000 000 | 23 | +20 | 1. e4 e6 2. d4 e5 3. d5 d6 4. c4 f5 |
| S3 | 8 000 000 | 27 | +2 | 1. e4 c6 2. Ne3 e6 3. g3 Nf6 4. c4 d5 |
| S4 | 32 000 000 | 32 | -10 | 1. e4 f5 2. exf5 d6 3. Ne3 Nh6 4. f6 Rxf6 |
| S5 | 128 000 000 | 41 | -12 | 1. e4 f5 2. exf5 Nh6 3. Ne3 d6 4. c3 Nxf5 |
| S6 | 400 000 000 | 50 | -2 | 1. e4 f5 2. exf5 Nh6 3. Ne3 d6 4. c3 Nxf5 |
| S7 | 800 000 000 | 57 | 0 | 1. e4 f5 2. exf5 Nh6 3. Ne3 d6 4. c3 Nxf5 |
| S8 | 1 600 000 000 | 57 | 0 | 1. e4 f5 2. exf5 Nh6 3. Ne3 d6 4. c3 Nxf5 |
Deep verification
The search ladder reaches 1.6 billion nodes; admission needs a 4-billion rung and two further engines on top of that. Beyond even that, every pair was re-checked at budgets up to ten times larger and in thousands of self-play games. This section shows what each check returned for this pair.
| Nodes | Eval, cp |
|---|---|
| 4 000 000 000 | 0 |
| 8 000 000 000 | not checked |
| 16 000 000 000 | not checked |
This pair stays within the ±5 cp corridor up to 4 000 000 000 nodes.
Independent engines, run on the same position:
- Berserk 14: +6
- Lc0 0.32.1: -2
Independent confirmations: 3 of 3. An engine counts as confirming when its reading of the pair is closer to equality than its own reading of a typical symmetric Chess960 position (+10 for Berserk, +18 for Lc0). Where only one engine confirms, the pair is balanced according to that engine alone, and this page says so.
Own weight of each setup, measured against the classical array: White +9, Black +10, difference -1. A balanced pair needs White's setup to be weaker by about the price of the first move.
Extended self-play: 10 games, 0 White wins, 10 draws, 0 Black wins, White scored 50.0%.
Best first moves
The 3 best first moves for White, searched together at 400 000 000 nodes.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | +2 | 43 | 1. e4 f5 2. exf5 d6 3. Ne3 Nh6 4. c3 Nxf5 5. Bd3 Qf7 |
| 2 | -7 | 42 | 1. Nb3 f5 2. c4 c6 3. Qc2 Qg6 4. g3 Nf7 5. Ne3 d6 |
| 3 | -12 | 42 | 1. c4 f5 2. Nb3 c6 3. Qc2 Qg6 4. g3 Nf7 5. f4 e5 |
Main-line play-out
11 moves, 5 000 000 nodes per half-move. Largest |evaluation| 24 cp, mean 2.8 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | g3 | +1 | c6 | -24 |
| 2 | c4 | -9 | f5 | -8 |
| 3 | Nb3 | -10 | f4 | 0 |
| 4 | gxf4 | 0 | Qh5 | 0 |
| 5 | Nc3 | 0 | Bxf4 | 0 |
| 6 | h4 | 0 | Nf6 | 0 |
| 7 | e3 | 0 | Qf3 | -10 |
| 8 | Rh3 | 0 | Qg4 | 0 |
| 9 | Rh1 | 0 | Qf3 | 0 |
| 10 | Rh3 | 0 | Qg4 | 0 |
| 11 | Rh1 | 0 | Qf3 | 0 |
Engine self-play
10 games at 500 000 nodes per move: White won 0, drawn 10, Black won 0 — White scored 50.0%. Average length 37.8 moves.
Sample game 1 (1/2-1/2)
1. c4 f5 2. Nb3 d6 3. d4 Qf7 4. f4 Nf6 5. g3 c6 6. Bg2 O-O 7. d5 e5 8. dxe6 Bxe6 9. Qc2 Bc7 10. Bd4 Rae8 11. Ne3 Bd7 12. Nxf5 Ng4 13. Nh4 Bd8 14. Nf3 Bf6 15. Bg1 Ne3 16. Bxe3 Rxe3 17. Rd1 Qe7 18. Rd3 Nf7 19. Nfd4 Nh6 20. Qd2 Rxd3 21. Qxd3 g5 22. O-O Ng4 23. e4 gxf4 24. Rxf4 Bg5 25. Rxf8+ Qxf8 26. Nf5 Be3+ 27. Kf1 Qf6 28. Qc3 Qf7 29. Bf3 Nxh2+ 30. Kg2 Nxf3 31. Qxe3 Bxf5 32. exf5 Ne5 33. Qg5+ Qg7 34. Qd8+ Qf8 35. Qg5+ Qg7 36. Qd8+ Qf8 37. Qg5+
Sample game 2 (1/2-1/2)
1. c4 f5 2. Qc2 c6 3. f3 Qf7 4. Nb3 d6 5. e3 Nf6 6. d4 e5 7. dxe5 dxe5 8. e4 O-O 9. exf5 e4 10. fxe4 Nxe4 11. Ne3 Bxf5 12. Nxf5 Qxf5 13. O-O-O Qxf1 14. Qxe4 Qf7 15. Qc2 Be5 16. Kb1 Ng6 17. a3 Qf5 18. g3 Qxc2+ 19. Kxc2 Bf6 20. Bd4 Bxd4 21. Rxd4 Ne5 22. Rhd1 Rf2+ 23. R1d2 Raf8 24. Re4 R8f5 25. c5 Nd7 26. Rxf2 Rxf2+ 27. Kb1 h5 28. Re7 Rf7 29. Re4 Rf2 30. Re7 Rf7 31. Re4
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 126 / 900 in the app's encyclopedia, then choose how to play.
- Local game — two players on one device, with a clock.
- With a mentor — a clearly labelled training bot with hints, at your level.
- Challenge a friend — an online game by link; both players get the same pair, colours swap on rematch.
Play this pair against the computer, right here Play a friend
FEN (Shredder, castling rights by rook files): rbbkqrnn/pppppppp/8/8/8/8/PPPPPPPP/NQRNKBBR w CHaf - 0 1
Mirror twin: White 836 vs Black 62 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 500.