user14463: I use Arena for tournaments between chess engines.
The interesting thing is that in different 64-bit multi-processor computers ranking is slightly different. I was expecting that they should be the same.
Do you have any idea why this happens?
As an example Booot 6.2 64-bit loses most of the games on a low end new PC.
However in a stronger PC with newer 'Core i7' CPU it can even have the same score as Stockfish 8 (which most of the time is in top of tables).

user825: How many games did you play? Unless your tournament had enough games, your conclusion wasn't statistically significant.
It's common misconception that Stockfish would play better chess than weaker engines in a short computer chess tournament. This is wrong and wrong. Stockfish's higher ELO means it's expected to play better chess. Anything could happen in a short match or tournament.
Magnus Carlsen has the highest FIDE ELO, but that doesn't mean he wins everything. He'd lost to Bu in the 2017 World Cup in a 2-games mini-match, but do you really think Bu is a stronger chess player than the World Champion?

14463: <p>I use Arena for tournaments between chess engines.</p>

<p>The interesting thing is that in different 64-bit multi-processor computers ranking is slightly different. I was expecting that they should be the same.</p>

<p>Do you have any idea why this happens?</p>

<p>As an example Booot 6.2 64-bit loses most of the games on a low end new PC.
However in a stronger PC with newer 'Core i7' CPU it can even have the same score as Stockfish 8 (which most of the time is in top of tables).</p>
 825: <p>How many games did you play? Unless your tournament had enough games, your conclusion wasn't statistically significant.</p>

<p>It's common misconception that Stockfish would play better chess than weaker engines in a short computer chess tournament. This is wrong and wrong. Stockfish's higher ELO means it's <strong>expected</strong> to play better chess. Anything could happen in a short match or tournament.</p>

<p>Magnus Carlsen has the highest FIDE ELO, but that doesn't mean he wins everything. He'd lost to Bu in the 2017 World Cup in a <strong>2-games</strong> mini-match, but do you really think Bu is a stronger chess player than the World Champion?</p>
