White 123 vs Black 596
White starts from setup 123 (NQRNBKRB), Black from setup 596 (RBBQNKRN). In the encyclopedia since 2026-10-21: 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. 123, Black by position No. 596, 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 #123 N Q R N B K R B
King on the f-file, rooks on c, g, queen on the b-file; one 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 123 gives White +0.25 (Morozov Balance Index, 400M nodes).
Black: setup #596 R B B Q N K R N
King on the f-file, rooks on a, g, queen on the d-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 596 gives White +0.11 (Morozov Balance Index, 400M nodes).
Why the pair is balanced
At the deepest rungs (400M, 800M, 1.6B nodes) the evaluation never left ±5 centipawns of equality, reaching search depth 52.
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 agreed early: from 100 thousand to 128 million nodes the evaluation never left ±10 cp.
For comparison, in symmetric play setup 123 gives White +0.25 and setup 596 gives White +0.11: 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 c4, and 2 first moves are within 10 cp of it.
Along the engine's main line (30 moves) the largest swing was 93 cp (around move 28), ending at +52 cp — the position stays playable for both sides.
Engine self-play agrees: 10 games, White won 2, drawn 8, Black won 0 (White scored 60.0%).
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 | 15 | +10 | 1. c4 O-O 2. g3 c6 3. O-O e5 4. d4 f5 |
| S1 | 500 000 | 19 | 0 | 1. c4 a5 2. g3 O-O 3. d4 c6 4. O-O d5 |
| S2 | 2 000 000 | 24 | +2 | 1. c4 O-O 2. g3 f5 3. d4 c6 4. f4 a5 |
| S3 | 8 000 000 | 29 | +6 | 1. g3 O-O 2. c4 a5 3. d4 d6 4. Qd3 f5 |
| S4 | 32 000 000 | 37 | 0 | 1. c4 O-O 2. g3 c6 3. O-O d5 4. cxd5 cxd5 |
| S5 | 128 000 000 | 41 | -8 | 1. c4 O-O 2. g3 c6 3. d4 d5 4. Bg2 dxc4 |
| S6 | 400 000 000 | 46 | -3 | 1. c4 O-O 2. g3 a5 3. d4 d6 4. f4 Nf6 |
| S7 | 800 000 000 | 48 | -5 | 1. c4 c6 2. g3 O-O 3. O-O f5 4. f4 a5 |
| S8 | 1 600 000 000 | 52 | 0 | 1. c4 c6 2. g3 O-O 3. O-O f5 4. f4 a5 |
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: -1
- Lc0 0.32.1: +8
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 +43, Black +64, difference -21. A balanced pair needs White's setup to be weaker by about the price of the first move.
Extended self-play: 10 games, 2 White wins, 8 draws, 0 Black wins, White scored 60.0%.
Best first moves
The 3 best first moves for White, searched together at 400 000 000 nodes.
| # | Eval, cp | Depth | Main line |
|---|---|---|---|
| 1 | 0 | 44 | 1. c4 O-O 2. g3 c6 3. O-O d5 4. cxd5 cxd5 5. Bxd5 Qxd5 |
| 2 | 0 | 44 | 1. g3 O-O 2. c4 c6 3. O-O d5 4. cxd5 cxd5 5. Bxd5 Qxd5 |
| 3 | -11 | 44 | 1. d4 c5 2. g3 cxd4 3. Nb3 d5 4. Nxd4 e5 5. Nb5 O-O |
Main-line play-out
30 moves, 5 000 000 nodes per half-move. Largest |evaluation| 93 cp, mean 38.0 cp, final +52 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | g3 | -1 | O-O | 0 |
| 2 | c4 | 0 | c6 | 0 |
| 3 | O-O | +9 | a5 | +9 |
| 4 | d4 | +12 | f5 | +5 |
| 5 | f4 | +5 | e6 | +2 |
| 6 | a4 | -4 | d6 | -6 |
| 7 | Qd3 | -8 | d5 | -8 |
| 8 | Nf2 | +6 | Nf6 | +24 |
| 9 | Nb3 | +20 | Nf7 | +18 |
| 10 | c5 | +22 | Bc7 | +19 |
| 11 | Qd1 | +21 | Kh8 | +22 |
| 12 | Nd3 | +17 | Bd7 | +23 |
| 13 | Bd2 | +27 | Be8 | +17 |
| 14 | Ne5 | +25 | Rg8 | +21 |
| 15 | Bf3 | +22 | h6 | +19 |
| 16 | h4 | +17 | Ne4 | +22 |
| 17 | Bxe4 | +41 | dxe4 | +25 |
| 18 | Kf2 | +60 | b5 | +80 |
| 19 | cxb6 | +78 | Bxb6 | +78 |
| 20 | Be3 | +82 | Rb8 | +40 |
| 21 | Rc3 | +65 | Kh7 | +61 |
| 22 | Nc4 | +64 | Qd5 | +71 |
| 23 | Qc1 | +74 | Nd6 | +72 |
| 24 | Nxb6 | +68 | Rxb6 | +69 |
| 25 | Nd2 | +72 | Nc8 | +71 |
| 26 | Rc5 | +70 | Qd8 | +60 |
| 27 | Nc4 | +61 | Rb4 | +85 |
| 28 | Bd2 | +93 | Qxd4+ | +83 |
| 29 | Be3 | +59 | Qd8 | +64 |
| 30 | Rd1 | +53 | Qc7 | +52 |
Engine self-play
10 games at 500 000 nodes per move: White won 2, drawn 8, Black won 0 — White scored 60.0%. Average length 48.3 moves.
Sample game 1 (1/2-1/2)
1. g3 c6 2. O-O a5 3. c4 O-O 4. d4 f5 5. f4 e6 6. c5 b6 7. cxb6 Qxb6 8. Nb3 Nf6 9. Qc2 Ng6 10. Bf2 Qd8 11. Bf3 Ne7 12. Nc3 Ba6 13. Na4 Bb5 14. Nac5 a4 15. Nd2 Ned5 16. Rfe1 Re8 17. a3 d6 18. Nd3 Bc7 19. e4 fxe4 20. Nxe4 Ba5 21. Red1 Rb8 22. h4 Nxe4 23. Bxe4 Rf8 24. b4 axb3 25. Qxb3 Qe8 26. a4 Nc3 27. Rxc3 Bxd3 28. Rdxd3 Rxb3 29. Rxb3 Qa8 30. Rd1 d5 31. Bf3 Rb8 32. Re3 Kf7 33. Bg4 Rb2 34. Bxe6+ Kf8 35. Bg4 Bb4 36. Re6 Qxa4 37. Rc1 Rc2 38. Rf1 Qa3 39. h5 Bc3 40. Rb1 Rc1+ 41. Rxc1 Qxc1+ 42. Kg2 Qb2 43. Re2 Qb4 44. Re6 Qb2 45. Re2 Qb4 46. Re6
Sample game 2 (1/2-1/2)
1. O-O d5 2. c4 c6 3. cxd5 cxd5 4. Nc3 Ng6 5. g3 e6 6. Qc2 Bd7 7. Nb3 O-O 8. Nc5 Bc6 9. b4 Be5 10. b5 Bd7 11. Qd3 Rc8 12. Nxd7 Qxd7 13. e4 Bxc3 14. Rxc3 Rd8 15. exd5 Ne7 16. Ra3 b6 17. Qb3 exd5 18. Ra4 Nd6 19. Rb4 Ne4 20. Bg2 Nc5 21. Qb1 Rfe8 22. f3 Ng6 23. Bf2 Re2 24. Rd1 h5 25. h4 Ree8 26. Bf1 Ne5 27. Kg2 Nc4 28. Bxc4 dxc4 29. Rxc4 Nd3 30. Be3 Nb2 31. Qxb2 Rxe3 32. dxe3 Qxd1 33. Rd4 Rxd4 34. exd4 g6 35. Kf2 Qd3 36. a3 Kg7 37. a4 Kh7 38. Qb4 Kg8 39. f4 Kg7 40. Qd6 Qd2+
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 123 / 596 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): rbbqnkrn/pppppppp/8/8/8/8/PPPPPPPP/NQRNBKRB w CGag - 0 1
Mirror twin: White 833 vs Black 270 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 493.