Don't know much on EM on paralell processors, have heard some stuff, but have also some experience that speed of the processor is not the only speed you should be concerned about. You can use PIV on 2.6GHz insted of PVI on 1.7 GHz and have much slower simulations! It is the speed of the bus and the speed of the memory (RDW is prefered) that can kill any processor speed increase. The speed of processor is progressing much faster that the speed of two other things mentioned, so I don't expect any great improvement soon.
In general, computers for mass productions are optimized for speed that average user will demand - speed in graphics, animation, CD and DVD reading and other popular demands. Specialized solutions work better but sometimes it is marginal for the price you pay. I still remember a large vasted sum of money I paid for Pentium-Pro Processor - 6 months later a regular and 3 times cheaper one was more effective! Not to mentioned the price of dedicated motherboard!
Conclusion: Don't dream on paralell computer that will work 20 times faster (that is what you really need), it will work 20% faster insted (and you will pay a great money for each percent there!)
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