News flash: they're all terribly strong! The mightiest of the lot is...well, it depends on your machine. IF you have a quad processor machine, then
Zap!Chess [sic] is the top dog with a 2995 rating.
If you're like me, however, and have a lowly single-processor machine, then
Rybka is the boss, only one point below Zap!Chess at 2994. Pretty remarkable: just as strong as ZC, yet with only one-fourth the processing power.
The gap between these two engines (in various versions) and the rest of the field is pretty substantial, with Deep Shredder 9 (on a dual-processor machine) and
Fritz 9 enjoying ratings in the 2850s. (Go
here for the details.) The good news for Shredder fans like me is that
Shredder 10 and its
Deep (i.e. multiprocessor) version will be sold by
ChessBase next week (on the 24th), and the product blurb promises an 80 point increase on all previous versions. That would place it around 2930-2940, not
too far behind Zap! and Rybka.
So what should the customer do? That depends on several factors. If you don't have any ChessBase software, then if you have a single processor machine, I'd recommend waiting a few days for Shredder. That way you get their excellent interface, two one-year accounts on their
Playchess server (where I do my
Monday night shows), a database, and some nifty programming allowing much faster tablebase access than usual for chess engines.
If you have ChessBase software
and a multiprocessor machine, then Zap!Chess might well be the best choice, as its programmer specially designed the engine for that very purpose.
If you're already set up with ChessBase and, like me, are still in the stone ages (i.e. using a single processor machine), then while Shredder will give it a run for the money if the promise comes true, Rybka is the king of the hill, at least for the moment. Further, when you purchase Rybka, you're purchasing a subscription, and thus as new mini-releases come available (as they have with some frequency thus far), you get them right away.
As I wrote at the end of my
previous post, however, tools are our servants, not our masters. And while chess engines and other chess software make wonderful tools, when we let them do our work for us, we've gone off the rails. If you want to improve, then the correct order is minds first and second, computers third, and minds again in fourth. (Decoded, I mean this: first, play; second, analyze your games; third, check your moves and analysis (interactively!) with the computer; fourth, extract lessons from the computer analysis. Rinse and repeat.)