Building a multi-cpu machine

R

Russell

Geek Trainee
I am interested in building a multi-cpu machine. I would like to do a little research (just a hobby kind of thing) on scalable search in game playing programs, like chess or checkers, and see how much faster programs get on two or four cpus. The only problem is, I don't have a machine with more than one cpu. So my need is not for a top of the line machine, but just one that has multiprocessor support. So a few questions...

I don't know much about building a multi-cpu machine. Are there any significant differences, other than the need for a mobo that supports it (and multiple cpus)?

Would I be able to get slower multi-cpu machines cheaper than I would if I wanted to build dual 2GHz machines or quad (whatever the latest quad cpus run at) MHz? Or is the difference only marginal? What I mean is, I'm only testing scalability (how much faster it runs on dual cpus compared to single cpu, or quad cpus compared to duals, etc.) so if it's a dual 100 MHz machine that'll work just fine. Of course, if it's only marginally more expensive to get something faster, then I might as well go ahead and get the newer stuff so I can actually use it for more than casual experimentation. Can I save money here or would the savings not be worth the trouble?

Lastly, I'd like to know what my options are between dual and quad systems. I'd like to have a quad so I could test scalability more, but it seems like the only quad machines I've ever seen use cpus that are significantly slower than the latest single cpu. Ex. we have a unix box at school that is a quad, but it has 450MHz cpus in it. The only thing is, that box is way more expensive than it would be for me to get a top of the line dual, so the slower cpus aren't any savings here. Is this example common? Do quad machines always use significantly slower cpus?

Anyway, I guess you can get the drift of what I'm trying to find out. If you could help guide me in the right direction I would appreciate it very much. Thanks.

Russell
 
A program must be coded to take advantage of more than 1 CPU for it to be of use. The advantage of 2 or more CPU's is the ability to multitask better. You have 2 or more workers to do the tasks.
If the program happens to take advantage of an extra processor, then it would be advantageous to have that 2nd one. These programs are generally on the professional level, and are stuff like Photoshop for one. There aren't many games that take advantage of dual processors, but Quake 3 can. It doesn't really provide anything significant---if it works. The coding for it wasn't the best, and I haven't gotten it to work with a multiprocessor box.

If you want to experiement with multi processors, I really wouldn't spend a ton of money getting a top of the line box.
If you're intrested in a quad box to toy with, you can still find Pentium Pro's (Normal Pentium---socket 7---will not work) on ebay.
Another slightly easier proposition to do would be do find an Abit BP6 and find any PPGA Celeron 533 or slower----please note that the 533A are FC-PGA chips and have been totally stripped of any SMP capability. The 533A's and on will not work in SMP.

What differences really depend on what you go with. Older P2/P3 Xeon mtoherboards required a voltage regulator---which you may have to track down several. This also applies to the Pentium Pro's.

Most likely, you won't notice programs being faster so much as simply being able to run a lot more at once.
Dual processing is fun to play around with. A great resource here is 2CPU. There's so much information on dual processors that I simply cannot explain, but that their message board can. There are a number of people that deal with this stuff on a daily basis, so just buy browsing you should be able to find the information.
 
Thanks Big B. 2cpu looks like it will be a very good resource.

Yeah I know all about (well, maybe not ALL about) multithreading. I know how chess programs take advantage of multiple cpus, but not things like quake or photoshop. This is just a hobby of mine, writing a chess playing program, and adding SMP support is something I find interesting, not to mention the program will play better on two cpus than one (well, not on a dual 100MHz, but...). I'm interested in testing current algorithms that are published in academic journals on scalable search in games. Usually a dual will run this kind of searching game anywhere from 1.6-1.9 times faster, and the quad only runs about 3 times as fast, and when you go beyond that you get heavily diminishing returns, so I think there's room for improvement.

Anyway, thanks for the reply.
 
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