White 65 vs Black 39
White starts from setup 65 (BNNBRKQR), Black from setup 39 (NNBQRKRB). In the encyclopedia since 2026-10-09: 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. 65, Black by position No. 39, 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 #65 B N N B R K Q R
King on the f-file, rooks on e, h, queen on the g-file; one bishop starts in a corner; the knights start on central files. Castling follows the Chess960 rule: king and rook end on the classical squares. In ordinary symmetric play setup 65 gives White +0.26 (Morozov Balance Index, 400M nodes).
Black: setup #39 N N B Q R K R B
King on the f-file, rooks on e, g, queen on the d-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 39 gives White +0.10 (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 60.
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 ±7 cp.
For comparison, in symmetric play setup 65 gives White +0.26 and setup 39 gives White +0.10: with both sides on the same rank the first move is worth something. In this pair Black's own setup absorbs that edge completely.
The engine's first choice for White is b4; the alternatives are slightly weaker but keep the game level.
Along the engine's main line (25 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 | 17 | -6 | 1. f4 Nc6 2. b3 O-O 3. Qf2 e5 4. fxe5 g6 |
| S1 | 500 000 | 19 | -4 | 1. f4 Nc6 2. b3 e5 3. Qf2 O-O 4. O-O exf4 |
| S2 | 2 000 000 | 23 | +7 | 1. f4 Nc6 2. d4 Nb6 3. b3 d6 4. e4 g5 |
| S3 | 8 000 000 | 30 | +5 | 1. b4 Nb6 2. f4 d6 3. Qf2 e5 4. O-O O-O |
| S4 | 32 000 000 | 37 | -4 | 1. b4 Nb6 2. f4 d6 3. Qf2 e5 4. O-O O-O |
| S5 | 128 000 000 | 43 | 0 | 1. b4 Nb6 2. f4 d6 3. Qf2 e5 4. O-O O-O |
| S6 | 400 000 000 | 51 | -2 | 1. b4 Nb6 2. f4 d6 3. Qf2 e5 4. O-O O-O |
| S7 | 800 000 000 | 59 | 0 | 1. b4 Nb6 2. f4 d6 3. Qf2 e5 4. O-O O-O |
| S8 | 1 600 000 000 | 60 | 0 | 1. b4 Nb6 2. f4 d6 3. Qf2 e5 4. O-O O-O |
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 | -1 |
| 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: -8
- Lc0 0.32.1: +13
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 +55, Black +63, difference -8. 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 | +3 | 44 | 1. b4 d6 2. f4 Nb6 3. Qf2 e5 4. O-O O-O 5. e3 g6 |
| 2 | -10 | 43 | 1. f4 Nc6 2. Qf2 g6 3. O-O d6 4. e3 O-O 5. d4 e5 |
| 3 | -14 | 43 | 1. f3 Nc6 2. d4 g6 3. b3 O-O 4. e3 Nb6 5. Qf2 e5 |
Main-line play-out
25 moves, 5 000 000 nodes per half-move. Largest |evaluation| 24 cp, mean 6.0 cp, final 0 cp.
| # | White | cp | Black | cp |
|---|---|---|---|---|
| 1 | f4 | +11 | Nc6 | -19 |
| 2 | Qf2 | -7 | g6 | -9 |
| 3 | e3 | -3 | d6 | 0 |
| 4 | O-O | -8 | O-O | -11 |
| 5 | d4 | -17 | e5 | -19 |
| 6 | dxe5 | -18 | dxe5 | -20 |
| 7 | b3 | -8 | Nb6 | -22 |
| 8 | c4 | -20 | Bf6 | -24 |
| 9 | Bc3 | -18 | Nd7 | -9 |
| 10 | Bf3 | -10 | e4 | -10 |
| 11 | Be2 | -7 | Qe7 | -15 |
| 12 | Rd1 | -8 | Rd8 | -8 |
| 13 | a3 | 0 | Bxc3 | 0 |
| 14 | Nxc3 | 0 | Nb6 | 0 |
| 15 | Nd5 | 0 | Qxa3 | 0 |
| 16 | Nf6+ | 0 | Kg7 | 0 |
| 17 | Rxd8 | 0 | Rxd8 | 0 |
| 18 | Nxe4 | 0 | a5 | 0 |
| 19 | f5 | 0 | Bxf5 | 0 |
| 20 | Bg4 | 0 | Bxe4 | 0 |
| 21 | Qxf7+ | 0 | Kh6 | 0 |
| 22 | Qf4+ | 0 | Kg7 | 0 |
| 23 | Qf6+ | 0 | Kh6 | 0 |
| 24 | Qf4+ | 0 | Kg7 | 0 |
| 25 | Qf6+ | 0 | Kh6 | 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 43.0 moves.
Sample game 1 (1/2-1/2)
1. b3 e5 2. f4 Nc6 3. Qf2 O-O 4. O-O exf4 5. Nd3 g5 6. Bxh8 Kxh8 7. h4 gxh4 8. Nxf4 Nb6 9. e4 d6 10. Nh5 Re6 11. Nc3 Rg6 12. Nf6 Nd7 13. Ncd5 Nxf6 14. Nxf6 Kg7 15. Nh5+ Kh8 16. Nf6 Kg7 17. Nh5+ Kh8
Sample game 2 (1/2-1/2)
1. f4 Nc6 2. Qf2 g6 3. O-O O-O 4. e3 d6 5. d4 e5 6. dxe5 dxe5 7. b3 Nb6 8. c4 Bf6 9. Bc2 Nb4 10. Be4 Nd7 11. Bc3 a5 12. a3 Nc5 13. Nd2 Nba6 14. fxe5 Bxe5 15. Bxe5 Rxe5 16. Bc2 f5 17. e4 fxe4 18. Qxf8+ Qxf8 19. Rxf8+ Kxf8 20. h3 Re8 21. Re3 Bf5 22. g4 Rd8 23. Nf1 Bd7 24. Na2 b5 25. b4 axb4 26. axb4 Nd3 27. cxb5 Bxb5 28. Rxe4 Be8 29. Bxd3 Rxd3 30. Re3 Rd4 31. Ng3 c6 32. Ne2 Rd2 33. Nac3 Nxb4 34. Ne4 Rd3 35. Kf2 Bf7 36. Nf4 Rxe3 37. Kxe3 Ke7 38. Kd4 Bd5 39. Nxd5+ Nxd5 40. Kc5 Nf6 41. Ng5 h6 42. Nf3 Ne4+ 43. Kd4 Ng5 44. Ne5 Kf6 45. Nxc6 Nxh3 46. Ke3 Ng5 47. Nb4 Ne6 48. Nd3 Kg5 49. Ne5 Kf6 50. Nd7+ Kg5 51. Kf3 Nd4+ 52. Ke4 Nb3 53. Ne5 Nc5+ 54. Kd4 Kf6
Play it in the CH960 app
Open this page on a phone with the CH960 app installed, or find pair 65 / 39 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): nnbqrkrb/pppppppp/8/8/8/8/PPPPPPPP/BNNBRKQR w EHeg - 0 1
Mirror twin: White 891 vs Black 914 — a different position (castling squares are fixed), not evaluated by the search.
Current place in the live balance rating: 286.