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[Shaun Brewer]

Tord,

a couple of old examples on a Core 2 Duo (e6300 at 2186mhz).

- dual boot XP Pro and XP Pro 64-bit

256mb hash

Rybka 2.1c

64-bit OS

32-bit - Depth: 20 00:15:08 113900kN
64-bit - Depth: 20 00:08:29 113900kN

Nothing short of stunning although Vas has mentioned he writes for 64-bit with no consideration for 32-bit performance and it is up to the compiler to do its best.

32-bit OS

Depth: 20 00:14:57 113900kN

Naum 2.0

64-bit OS

32-bit - Depth: 20/51 00:19:14 1139437kN
64-bit - Depth: 20/51 00:18:29 1139437kN

32-bit OS

Depth: 20/51 00:19:01 1139437kN

I noticed a 1-2% hit for running a 32-bit engine under the 64-bit OS rather than a native 32-bit OS.

Recently I tested Loop 13.5 - I do not have the figures at hand (actually I think I posted them somewhere on the forum) anyway I found the 32/64-bit versions to run almost identically with the 32-bit compile very slightly faster. My guess was that the 64-bit compile was better optimised for AMD?

Shaun