You would be better off getting a motherboard that supports hyperthreading (like the ASUS P4PE). For around $200, this motherboard has onboard gigabit ethernet, Soundmax sound system, the new Serial ATA interface for hard-drives (no more thick cables! yay!) and a host of other features. The 3.06Ghz Pentium IV chip can be had for $700 -- but will drop in February. This chip is basically two chips under one hood -- and Windows XP "CORPORATE EDITION" will recognize the chip as two virtual processors. Intel put hyperthreading into many of their Pentium IV's, but this is the first chip to have it unlocked. I know of no way to unlock it on other chips. If you got a dual P4 motherboard that supported hyperthreading, you would have a virtual quad-processor motherboard capable of a lot of MIPS.
This is slightly innacurate. While it is true that if the program is not multi-threaded, the "only" software that would benefit from the multiple CPU is the OS, assuming it too is multi-threaded, and that does make some difference. As far as Hyperthreading, it is an interesting technolgy. I do not have a Hyperthread enabled MB yet so I cannot run tests. However, 5 - 10 times speed improvements would be astonishing to me under all but the most superficial of circumstances. All of the P4 already have advanced pipelining etc. How much _could_ hyperthreading add in the absence of another CPU? Probably less than a 20% improvement, if that... nitro
The 5x-10x example was just an extreme real-world example of how someone could benefit with two CPU's while running concurrent applications. The Hyperthreading chips actually have a second copy of almost every critical function on the chip. According to Intel's white paper on HD, it is exactly the same as having two physically seperated CPU's working together. Actually, this would be slightly faster because the pathways between both CPU's are much shorter since they are being housed on the same CPU. Even though it is one CPU, it is really two CPU's. Efficient multi-threaded software programs would be a real-world increase of between 40-80% according to Intel. http://www.tomshardware.com has an excellent write-up on the benefits of hyperthreading. The only downside is the HEAT.
Toms hardware gets 50% of his revenue from Intel so thats not a good web site for unbiased opinion. Maybe Ace's hardware for some real world insite (best technical boards for geeks on the web ) and as for the Hyperthreading ,all claims of above 5%-10% are from Intel themselves. Check out Sisoft's site for their own benchmarking of hyperthreading ,a little different answer. Also "OVER AT THE US trademark and patent office, there's a slightly elderly patent successfully filed by AMD back in 1999 which indicates that the firm could provide hyperthreading for its processors, if it should so wish. The patent, numbered 5,944,816, entitled "Microprocessor configured to execute multiple threads including interrupt service routines", outlines how a CPU can execute multiple threads concurrently. It specifically says that in one test, a CPU executed at least two threads concurrently. The patent builds on a number of technical documents on simultaneous multithreading, including an Intel document from 1994 called Multiprocessor Specification. So will we see a hyperthreaded Clawhammer (Athlon64)? Well the patent seems to suggest that's not outside the bounds of possibility." This was lifted from The Inquirer . If your really want performance you might want to wait for Athlon64 around June 03.
The two critical components that an honest to goodness second CPU would give you are an extra honest to goodness L1 and L2 cache, which are missing in their "hyperthreading" partners (they share one L1 and one L2.) This alone blows just about all benefits out the window, as cache contention is "catastrophic" for the rest of the parallel pipelines (I assume INTC has found _some_ way around this and that "hyperthreading" is more than just a marketing gimmick.) If they did include those on one chip, _then_ , AFAIK, it would be the identical capacity of having the extra CPU. nitro