Dual Processing: Why?
Some weeks ago I spotted an advertisment of a local computer shop, offering systems with 'Pentium III 1200' and '1600 MHz'. Obviously there aren't any Pentium III processors at 1200 or 1600 MHz. The dealer was offering dual processor systems and decided to simply add up the clock speeds of the two system processors. A dual Pentium III 600 system became a 'Pentium III 1200' and a dual P3 800 became a 'Pentium III 1600'. Unfortuantely it doesn't work this way, my dear dealer! An ad claiming the above gets close to false advertising. What he doesn't tell his customers is that the vast majority of applications is utterly unable to benefit from dual-processor systems and even software that was specially designed for SMP is only able to run 20-85% faster than on a dual CPU system. Kinetix' 3D Studio Max is one of the exceptions, as it benefits tremendously from two CPUs. I included 3D Studio Max R2 to the benchmarks to show that two CPUs will almost halve the calculating time.
The vast majority of all applications does not support multiprocessing. Even if a title should be able to benefit from it, you will also need an operating system which supports SMP. That's basically Windows NT 4.0 (Workstation or Server), Windows 2000 (all versions) and Linux, if you compile a multiprocessing kernel. Forget about operating systems like Windows 95/98/ME if you want to go dual ...
In my opinion, the most valuable advantage of a dual CPU system is the better system response. Usually, you cannot run more than one or two CPU-intensive tasks smoothly, because your system simply cannot cope with more data load. With a dual processor system, you can easily run three tasks simultaneously and still have enough ressources left to do something else. A typical example would be an MP3-encoding session in the background, while you are working on your spread sheet. You canburn a CD and play a game at the same time. The more processor-intensive applications you are running at the same time the more you will benefit from a dual-processor system.
Upgrading Windows NT 4.0 For 2 CPUs
If you are using Windows NT 4.0 and want to upgrade to a dual system, you can either make a complete new system installtion or go the easier way:
In the NT Resource Pack you will find a little program called 'uptomp.exe ', which is supposed to upgrade a single processor installation to a multi processor one. Unfortunately the program comes with a bug, so you're required to download a patch from Microsoft's website. Don't expect 'uptomp.exe' to be all you need to run. As a nother example for Microsoft's inability to make WindowsNT user friendly enough this program will exchange the single-CPU-system kernel files with the SMP-system files from the installation CD. Thus you will have to upgrade to the service pack update you were using right after you ran 'uptomp.exe'.
If you should want to play it safe you could back up the following files previous to the switch to SMP:
- Hal.dll
- Kernel32.dll
- Ntdll.dll
- Ntoskrnl.exe
- Win32k.sys
- Winsrv.dll
All that 'uptomp.exe' does is replacing those files with their SMP-versions. Although Microsoft claims you will never be able to change back to single-processor, you actually can. Start another NT-installation from where you can access the files of your original installation and swap the above files back. After a reboot you will have your single-processor installation back.
Don't forget to make sure you have installed the right mass storage device drivers before you swap your motherboard. Without the correct HDD-drivers WindowsNT will be unable to boot.
Upgrading Windows 2000 For 2 CPUs
Fortunately Windows2000 is much less of a pain to change back and forth between single-processor and SMP configurations. Simply go into the Device Manager and find the item 'Computer'. With 'Change Driver' you can choose whichever system configuation you fancy by choosing 'show all available drivers'.
