I am considering the purchase of a new laptop to run Intel Core i7 and Windows 7 (64-bit, Professional). I have heard that eXtreme Gammon gets a big boost from the multi-threading capability of newer processors. My question is just how much? Dell Computer offers machines in the $1500 range that feature a two-core/four-hyperthread Intel Core i7 2620M (2.7GHz/4MB cache). Other machines run the four-core/eight-hyperthread Intel Core i7X "Extreme" 940XM (2.13GHz/8MB cache) for about $1,300 more!

Does anyone know how many threads eXtreme Gammon can launch effectively? Aside from the extra horsepower offered by the more expensive machines, would eXtreme Gammon benefit from the extra cores/hyperthreads? Exactly how many hyperthreads can eXtreme Gammon launch?

What about Windows 7? Does it make effective use of hyperthreads? Some Intel documentation recommend that you disable the processor's hyperthreading unless the operating system is explicitly capabable of managing hyperthreads. (See the hyperthreading article at wikipedia.org.)

Similarly, can eXtreme Gammon benefit from the 64-bit version of Windows?

Why don't you just ask Xavier himself?
contact@extremegammon.com

XG will use as many threads than your computer has, the limit is 64.

Using more threads does make a big difference. In particular, for rollouts (or level such as XGRoller) twice more core is almost twice more speed. 3-ply and lower analyze do not gain as much, but 4-ply and up do.
About hyper threading, do not worry about it, the OS will handle that (developers do not have to program specifically for HT). Note that an hyper threaded core is about 1.3 faster than a non-hyper threaded one.

The following is just a guideline, GameSite 2000 Ltd is not responsible of what computer you ultimately choose.
Intel newest processor (Sandy Bridge) does extremely well in its ratio performance/price
As a guideline, check the Passmark score (http://www.cpubenchmark.net/) the score scale almost linearly to XG speed (with a factor of 300):
For instance the i7 2620M has a score of 3318 and will get around 1,000,000 pos/sec.
The i7 940 XM has a score of 4506 and will yield 1,350,000 pos/sec

XG speed is 99% due to the processor, memory speed, hard drive speed has virtualy no effect.

XG is a 32 bits program and do not benefit from a 64 bits OS (but run without any issue on Win 7-64). However if you have 4 GB of memory or more, the OS will do a better job to use the memory.

Thanks, Xavier, for this very precise response.

As you know, I contacted you directly, but left this message here because I thought the information might be useful to others.

I assume these numbers are for XG1?
My numbers:
XG1 2,008,994
XG2 1,558,244 (22% slower)

Does the better accuracy of V2 completely compensate for the slower evals when doing rollouts? I.e. confidence reached at least 22% quicker?

Also my PC has 3gb of RAM. Do you know how much boost I would get from say 4gb or 6gb?

Thanks

XG2 is slower (by 1.20-1.25 depending of the machine).
however you will notice from www.extremegammon.com/xg2level.asp that V2 3-ply is stronger than V1 4-ply and 5 times faster. V2 3-ply-Red is stronger and a bit faster than V1 3-ply.

For RO, V2 converges much faster (typicaly 1.3 faster, but it will vary from position to position).
So for RO it takes 1.3^2 less games to get the same confidence and the overall speed gain is 1.3^2/1.225=1.38

I'm looking to buy a new machine, optimised for the only resource-demanding software I use nowadays, which is XG.

Question one - does anyone know if XG3 speed will depend on the same features as XG2 (mainly CPU speed x threads, whereas HDD, RAM and GPU speeds have no influence)?

Bonus question: does anyone know if XG3 has a real chance to be released sooner than in 3-4 years?

If answer to bonus question is "no", I guess I shouldn't bother with question one.

not sure if anyone can answer your questions other than developer; with that said, if you positively need to upgrade in the nearest future wait for Kaby Lake to come out in a couple of months - this way you'll be one less generation of CPU behind when XG3 is released

edit: just read XG2 documentation and it seems that it only uses 3 threads anyway so you don't even need to buy a flagship 8-thread processor