If this were a perfect world, we would all be completely self sufficient and we would never need to turn to anyone else for help. In reality, there isn't a single person out there that is completely self sufficient, at some point in life you'll have to face the facts and ask for help with at least one task that seems too overwhelming to attack alone.

Let's say you're a professor, and you've got a stack of exams to organize into piles according to grade. Although you could theoretically handle the task by yourself, it would surely expedite things if you had someone else helping you. So what do you do? Pick up the phone and call that assistant of yours, and now, in half the time, you've got a nicely organized section of your last exam. Fortunately, we can apply that same theory to computer hardware, more specifically, processing power.

Let's say your computer is working on a task, calculating the number of 4" wooden blocks that would fit end to end between the sun and the moon. Assuming that the length of such a calculation was beyond the time you had allocated to give that professor from the first example an answer (don't you just hate it when that happens?), you are now stuck with a bit of a dilemma. How can you make your system process that same calculation faster? Well, pick up the phone, call up your local hardware vendor, and place an order for another CPU. Now, in half the time, you've calculated that distance, since the task was split up between your two processors. That is an idealistic case when it comes to multiprocessing systems, however the case was made to prove a point, that the same theory from above can be applied to processing power, which brings us to a new solution for obtaining a faster system: multiprocessor systems.

Before we begin to talk about the wonders of a multiprocessor system we need to get a few requirements and stipulations mentioned in the open.

The first requirement of a multiprocessor system, is of course, a motherboard capable of accepting two or more processors. This requirement stems primarily from the capabilities of the chipset on the motherboard, for example, the Intel 440BX chipset is capable of supporting up to 2 Pentium II processors, with the Intel 450NX chipset supporting up to 4 Pentium II Xeon processors. Higher end Digital and Sun solutions even allow for systems to have up to 64-way multiprocessing capabilities, however you won't find any of those systems selling for anything even remotely affordable for a single user.

The price difference between a single and a dual processor motherboard is generally 30 - 40% due to the added components necessary for a multiprocessor motherboard. You have to remember that there must be some logic on the motherboard itself that will tell which processor to perform what operations, otherwise you'll have two equally powerful processors, with nothing to harness that power.

While on the topic of logic, to put an end to a common misconception now, there is a reason that there are no multiprocessor AMD K6-2 and Cyrix based systems. This reason is that the multiprocessor standard supported by AMD and Cyrix are different that the standard supported by Intel, and as with any conflict of standards, the larger company seems to always win the race. In this case, Intel holds the x86 market, therefore motherboard manufacturers produce motherboards based on their multiprocessor standard.

Secondly, you must have two identical processors. You cannot combine a Pentium II 450 and a Pentium II 350 in a single system, the two processors should ideally be of the same stepping and revision, although the basic requirement is that they are of the same general nature (i.e. two Pentium II 400's). Another misconception, which is often present as a topic in casual hardware discussions, is the proper naming system for a multiprocessor system. If you have a system with two Pentium II's clocked at 400MHz, it is incorrect to refer to the system as a Pentium II 800. That would imply that the system is running at a clock frequency of 800 million cycles per second (MHz) when in actuality, the system is still running at a 400MHz clock frequency, but with two processors. So the proper way of naming a multiprocessor system, such as the one from the previous example would be to indicate the number of processors in the system, as in a Dual Pentium II 400, or a Quad Pentium II 400, etc... Although this may seem like a trivial item to point out, there are a number of users out there that believe otherwise.

The third requirement of a multiprocessor system is an Operating System capable of taking advantage of two or more processors. What does this mean? Well, to put it bluntly, this means that Windows 98 is out of the question for a multiprocessor system. The second processor will simply sit there while the first processor handles the entire load of calculations Windows 98 chooses to throw at it. Windows 98 is not a multiprocessor OS. What does this leave? If you're bound to Windows, then Windows NT is a perfectly fine alternative, as is IBM's OS/2 Warp 4, Linux, Unix, BeOS, and Solaris (the AnandTech server actually runs off of a multiprocessor Solaris based machine) among other operating systems. In order to keep this article simple, we'll only focus on Windows NT based systems, in the future AnandTech may take a look at multiprocessor Linux and BeOS based systems as well.

Those are the three basic requirements for a multiprocessor system, with another stipulation for a high performing multiprocessor system being the active support for multiprocessor systems in your applications. Generally, professional applications such as Photoshop will support multiprocessor systems, however it is always good practice to check with the developer to find out if you'll actually receive any benefit from a multiprocessor system.

Now it's time to put all those theories to test, in August of 1997, the Intel 440LX chipset was the thing to get. Not even a year later, that 440LX was replaced by the 440BX which offered a few improvements that were absolutely "necessary" to have an up-to-date system (as to why the 440BX couldn't have been released instead of the 440LX, that's a different question). There were many users that for one reason or another, purchased a dual processor LX motherboard, in hopes of continuing their investment into the next year as a high end, performance system. However with the Pentium II 350, 400, and 450s requiring the 100MHz Front Side Bus, many users were left out in the cold as far as possible upgrades were concerned. The only option seemed to be, a new BX motherboard + Pentium II upgrade, an admittedly costly expense, with often times, not too great of a performance increase just to support the latest technology. Fortunately, if you had the foresight of purchasing a dual processor LX motherboard, or if you currently have an older Pentium II chip and don't feel comfortable ditching a $300 chip for a new motherboard and a $500 CPU, you still may have some hope left.

AnandTech put together a cost efficient dual processor system, made out of an older Dual Processor LX Motherboard (the Soyo SY-6KD) and two Pentium II processors running at 300MHz a piece, as well as an upgraded single processor BX system consisting of an affordable Shuttle HOT-661P BX Motherboard and a single Pentium II processor running at 450MHz, and put them both to the test. In the past, testing the efficiency of multiprocessor systems required either, benchmarks that were primarily raw CPU power and didn't reflect actual performance differences in real world applications, or customizing your own benchmarks, which could potentially be difficult to replicate by other users interested in comparing their systems. Luckily, the people over at the Ziff Davis Benchmark Operations included a new test in their Winstone 99 Benchmark Suite designed specifically for multiprocessor systems. Using the three programs which make up the Dual Processor Test Suite of Winstone 99, Adobe. Photoshop. 4.01, Bentley System's MicroStation. SE, and Microsoft. Visual C++. 5.0, AnandTech was able to pit the two identically configured systems head to head, in a battle where only one could emerge victoriously. The results were quite varied greatly, depending on the application run, however you can take a look for yourself at the benchmark results from the tests.

The rest of the system, other than the motherboards/processors mentioned above, was configured as follows:

• Memory Man PC100 SDRAM
• 9GB IBM Ultrastar Ultra Wide SCSI-3 HDD
• Adaptec 2940 Ultra Wide SCSI PCI Controller Card
• Matrox Millennium G200 (16MB) AGP Video Card
• Microsoft Windows NT Workstation 4.0 with Service Pack 3 Installed
• The latest device drivers as of January 3, 1999 were installed
• All tests were run at 1024 x 768 x 16-bit color at a 75Hz refresh rate

When outfitted with only 64MB of RAM, the memory hungry Windows NT refused to give AnandTech's upgraded Dual Processor system even a remotely noticeable advantage over its single processor counterpart in the benchmarks. As you'll quickly notice later on, RAM size does play a fairly large role in the benefit of a multiprocessor system. For a system with 64MB of RAM, regardless of what sort of professional you are, as long as you're running Windows NT, the clear upgrade path is a faster processor, a dual processor system won't give you much of a performance boost if any.

With 128MB of RAM, we can finally start to see some performance differences across the board. Under MicroStation SE, the performance of the Dual Pentium II 300 rose a full 34% while the performance of both single processor systems remained the same. CAD professionals will definitely appreciate the added memory size if they're using multiprocessor systems, due to the complexity of their designs, however the winner in the Computer Aided Design and Drafting category is once again the single processor Pentium II 450. The raw CPU power of a single 450 managed to outshine AnandTech's Dual Pentium II 300 system.

Moving along to Image Editing with Adobe Photoshop 4.01, the Dual Processor system is finally showing its muscle by taking a 4% performance lead over the Pentium II 450 system. Image editing professionals and graphics artists will definitely appreciate the responsive rendering and filtering times a dual processor system can produce, however as any graphics artists will be able to tell you, without enough RAM, the amount of CPU power you have when editing a 20MB+ image file (as the tests AnandTech conducted proved) is useless.

Under Microsoft Visual C++ 5.0, AnandTech's upgraded Dual Processor system took the spotlight once again with a 60% performance improvement over the base Single Pentium II 300 system, and a 17% improvement over the new Pentium II 450 system. Depending on what type of user you primarily are, the performance improvements the second processor offers may or may not be what you're looking for. In any case, the $200 investment of a second 300MHz Pentium II managed to outweigh the performance increase a $430 Pentium II 450 upgrade offered, not to mention the added cost of a new BX motherboard versus an older Dual LX board.

Once again, the raw FPU power of the Pentium II 450 is simply too great to be outdone by the performance of the Dual Pentium II 300 system under MicroStation (CADD), meaning most CAD designers will want to opt for a faster single CPU rather than two slower ones, however the ideal upgrade would be one to a dual Pentium II 450 system, unfortunately that is not always possible in which case a single 450 on a board capable of dual processors would be an excellent choice.

Graphics artists will be among those benefiting the most from a dual processor system here, AnandTech's Dual Pentium II 300 outperformed the 300MHz base system by 40% under Photoshop, and it distanced itself from the new Pentium II 450 system by an 9% performance differential, nothing too incredibly great, however when you consider the price difference between adding a second 300MHz processor and upgrading to a 450MHz system, it's not too shabby.

The situation under Microsoft Visual C++ remains virtually unchanged from the previous benchmark set with 128MB of RAM, illustrating a bit of the diminishing returns principle when it comes to memory upgrades. The Dual Pentium II 300 system still held on to its lead over the single Pentium II 450, but let's see how the jump to 384MB of RAM changes that, if at all.

With 384MB of RAM the standings remain virtually unchanged, and the performance gap between the Dual Pentium II 300 and the Single Pentium II 450 remains strong. The CAD performance of the Pentium II 450 keeps the Dual Pentium II 300 at a close second, and definitely offers an improvement over the base system, the Pentium II 300. Graphics artists will still get the most benefit out of a multiprocessor system, so long as it is equipped with enough RAM to meet the needs of your applications. Development professionals will also find a Dual Processor system more worth while of an upgrade, once again, provided that the system has a minimum of 128MB of RAM. It seems like the days when 64MB was an ideal target to shoot for are quickly coming to an end, for a professional system, anything under 128MB of RAM wouldn't be desirable, with the sweet spot being around 256 - 384MB of RAM.

...and just for comparison's sake, AnandTech conducted benchmarks with 512MB of RAM, however there were absolutely no performance differences what-so-ever between the 384MB and 512MB systems, illustrating that the limit of the benefit of increased memory sizes in these types of applications was reached. This limit will vary according to the nature of your application usage, however for the tests AnandTech conducted, it seems as though anything above 384MB wouldn't produce too great of an improvement in performance for most professional users (web servers excluded).

Can a multiprocessor system be overclocked? Absolutely. However the difficulty of overclocking a system increases when you have a multiprocessor system, since you must take into consideration that not all of the processors in the system may be able to cope with the overclocked speed. Supermicro's dual processor BX boards do allow for overclocking through the use of increased Front Side Bus speeds (112MHz on their BX/GX boards), and the Soyo board that AnandTech used in the tests allowed for overclocking through the use of the 75MHz FSB setting. The Dual Pentium II 300 system overclocked fine to 338MHz using the 75MHz FSB, however if you're planning for your system to be used without a single crash, you may want to avoid the thought of overclocking entirely.

Another consideration to make when dealing with a multiprocessor system is heat. Naturally, both processors must have heatsinks and fans on them, however you also might want to consider improving the ventilation in the case they are stored in. Any multiprocessor system should have a large enough case so that the airflow inside the case isn't obstructed in any way, and as always, the larger the case, the better.

Who would've thought that a multiprocessor system would be considered a "poor-man's upgrade?" In lieu of the price drops on Intel's now discontinued older Pentium II processors, the performance adding a second processor to an older system would offer over buying a faster single CPU (possibly with a new motherboard) depends entirely on the nature of the applications you'll be running on your system. While the improvement in business applications won't be too wonderfully noticeable, graphics artists and development professionals will generally find that multiprocessor systems will end up giving them the most bang for their buck, especially in extending the life of their current systems. The performance improvement AnandTech's tests illustrated under CAD Drafting applications indicates that a single, more powerful CPU is more desirable than two slower processors, however the ideal solution in any of these cases would be an upgrade to a multiprocessor system using the fastest processors available at the time...but then again, the ideal solution isn't always the most practical.