bag's Flight Sim System

Here's a run-down on the system I'm currently using to run Microsoft Flight Simulator 5.1:


Many people are having great success in speeding up their Pentium CPUs by increasing the system clock speed, a process known as overclocking. To overclock your CPU, you simply set the system clock on your motherboard as if the CPU was stamped with a higher clock rating. At the higher system clock speed, all CPU-related functions will run faster by a ratio equal to the change in system clock speed. For example, if you increase the system clock speed from 100 MHz to 120 MHz, CPU-related functions will run 20% faster. In my case, I was able to successfully increase my system clock from 75 MHz to 90 MHz for a 20% increase in CPU speed.

For flight sims, the goal and main benefit of overclocking the CPU is to increase the display frame rate by reducing the CPU time involved in generating each frame. Or, equivalently, to allow for more detail in each frame without sacrificing frame rate. Either way, you get a smoother, more realistic simulation as the speed of the CPU increases. Of course, the CPU isn't the only factor in determining the frame rate, but it is a significant one. The other significant factors include the speed of your video adapter (the faster, the better) and the amount of main RAM you have (the more, the better). However, overclocking your CPU is probably the cheapest and easiest way to improve frame-rate.

So, how do you do it? Consult your motherboard documentation to find out which jumpers are involved in setting the system clock speed, or selecting the type of CPU. If your motherboard supports CPU types and/or speeds faster than your current CPU, then you're in luck. Just follow these steps:

  1. Save your work and powerdown your system.
  2. Open up your case and carefully change the jumpers to the next higher CPU type and/or speed setting as described in your motherboard documentation.
  3. Reassemble the system and start it up.
  4. Run the system for a while to make sure that everything is working. Try a few benchmarks to confirm the speed increase.
  5. If you're satisfied that everything is running OK, repeat the preceding steps for the next higher CPU type and/or speed.
  6. If your system malfunctions in any way, back off to the previous slowers settings that worked.

In my case, the Acer AP5C motherboard supports 75 MHz, 90 MHz, 100 MHz, 120 Mhz and 133 MHz CPU types. The selection is made with Jumpers 9, 10 and 11 and the documentation is very clear on the settings. I tried 90 MHz, 100 MHz and 120 Mhz. At 100 Mhz and 120 MHz, my system didn't boot -- the CPU didn't execute a single instruction of the BIOS code! So, I backed off to 90 MHz, where everything has been working just fine for weeks. Your mileage may vary.

WARNING! As the clock rate increases, so does the heat generated within the CPU. Therefore, if you don't already have a CPU heatsink and fan installed, I strongly urge you to install one before you start experimenting with overclocking!

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