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Overclocking and Upgrading For More Quake III fps

Overclocking the PIII 500E

Ok, the system is set back to 166Mhz on the graphics card, but still has the RAM at 128MB. I've changed the BIOS to 100Mhz on the FSB and have it showing 1.6v on the core voltage. The clock multiplier has been set to 5.0 to match the 500E. It's time to fire it up and get some benchmarks. The system now produces a 42.4 at 1024x768. This is a only 1.3fps increase from the system with the Celeron set at 464Mhz, but if we look at the 800x600 video mode we see that the fps is now at 60.7 instead of 47.1. That's a 13fps (28%) increase. Setting the graphics card to 178Mhz gives us 45.6fps at 1024x768, an additional 3fps from the 166Mhz setting. The 800x600 video mode is now at 63.4fps, another 3fps.

The next step up on the FSB available on the BH6 is 103Mhz (turbo enabled on the 100Mhz FSB), but let's move on to the next step, 112Mhz. There are other things besides whether a CPU is overclockable that can stop you from overclocking your CPU higher than its default rate. The external clock setting (FSB) in the BH6 BIOS shows beside the number a ratio in parentheses. This ratio is the FSB to PCI bus ratio. At 100Mhz the ratio is 1/3 which puts the PCI bus at 33Mhz, right where it should be. The 1/3 and 1/2 (1/2 is used by the 66Mhz buses) PCI ratios are the only two available in the BH6. When we move to the 112Mhz FSB setting the ratio is at 1/3 which gives us 37.3Mhz on the PCI bus. This is not too bad and shouldn't cause any problems with most PCI cards.

The first time I tried to boot at this speed (112 x 5.0 = 560Mhz), the PC locked up trying to bring up Windows 98. After pressing the reset button, the system successfully booted into Windows 98. Running the benchmarks at 166Mhz and 178Mhz on the graphics card at 1024x768 yielded 42.4 and 45.6 respectively. At 800x600 62.6 and 66.2 at the 166Mhz and 178Mhz graphics card settings respectively.

So why did Windows 98 give me some trouble the first time I tried to reboot. If you've been reading real closely, you may have noticed that I have not mentioned changing the AGP clock ratio during any of the BIOS settings for overclocking the CPU. At 66Mhz the AGP clock is set to use a 1/1 ratio with the FSB which puts the AGP bus at 66Mhz. When I set the FSB to 100Mhz for the Celeron 300A and 500E CPUs, I didn't change the AGP clock ratio setting. This put the AGP bus at 100Mhz, well over the standard 66Mhz setting. At this bus speed the Voodoo3 did not roll over and die, it just kept on running. However, when I set the FSB to 112Mhz and left the AGP ratio at 1/1, the Voodoo3 3000 started to object a little to being stressed at that level. This was also evident by the scolling bar shown at the bottom of the screen during the Windows 98 bootup. Part of it had a small area that was scrolling by in a black color instead of the normal blue and white. Normally at a 100Mhz front side bus setting or greater we would use the 2/3 AGP ratio which is the only other AGP ratio avialable on the BH6. This lowers the AGP bus back to 66Mhz at the 100Mhz FSB setting.

Does overclocking the AGP bus help our performance? Let's see. With the PIII 500E running at 500Mhz, the graphics card at 178Mhz, and the AGP clocked at 66Mhz I get 69.6 and 62.6 at 640x480 and 800x600 respectively. Setting the AGP to 100Mhz gives me 70.8 and 63.4, about a 1 fps increase. So, yes it will give some benefit in performance.

Back to the BIOS and lets change the FSB to 124Mhz (124 x 5.0 = 620Mhz) and make sure the AGP clock ratio is set to 2/3. This puts the AGP clock at 83Mhz which we know is fine with this Voodoo3. The PCI ratio is at 1/3 which puts the PCI bus at 41Mhz. Most PCI cards should still run at this setting, but you may run into some that will object to the faster bus. Running the benchmarks again with the graphics card set to 178Mhz now produces a 67.5 and 45.6 at 800x600 and 1024x768 repectively.

At 112Mhz and 124Mhz another item that can effect overclockability is your RAM memory. Most PC100 RAM should run at 112Mhz, although its only rated at 100Mhz. At 124Mhz, you need good quality PC100 RAM. The Samsung PC100 RAM that I'm using in this system runs at this speed with no apparent problems. So, can we push this system any further? The next FSB setting in the BH6 is 133Mhz. This is where you would normally go buy some PC133 RAM, but let's try our system at 133Mhz anyway.

At 133Mhz the AGP bus is now running at 88Mhz (133 x 2 / 3). We know from the previous testing done in this guide that this Voodoo3 will handle that with no problems. The PCI clock is now at 44Mhz (133 / 3). Again you may start to run into some problems with some PCI cards at this speed. Also, some IDE hard drives may have problems at this speed. Powering up this system finds no problems. The system posts and boots into Windows 98. If you remember at the beginning of this guide I mentioned the system had a SoundBlaster Live! Value sound card and a generic (cheap) network card. Neither of these seemed to have any problems running at the 44Mhz PCI bus speed.

OK, 133Mhz x 5.0 has the PIII 500E clocked at 667Mhz. That's not too bad. I believe that if we put this CPU on a quality motherboard with good PC133 RAM, that it would continue clock right on past the 667Mhz mark with no problems. Now, the benchmarks show 85.6 and 88.1 at 166Mhz and 178Mhz on the graphics card at 640x480. Originally with the Celeron 300A clocked at 300Mhz we could only get 32.1fps. The 800x600 and 1024x768 marks with the graphics card at 178Mhz shows 67.7 and 45.6. These are virtually the same numbers that were gotten at the 620Mhz CPU speed. Up until this point the CPU was limiting the graphics card at these resolutions. Now the graphics card is beginning to be the bottleneck.

One more step, this time backwards. I mentioned earlier that the 128MB of RAM was left in and haven't been giving any numbers to show the differences it may make at this CPU speed. So, removing 64MB of RAM to reduce the total RAM back to 64MB gives me 67.6 and 45.5 at 800x600 and 1024x768, virtually the same. At 640x480 there is a 2 fps drop. With the graphics card at 178Mhz the 1280x1024 video mode produced a max of 28.9 which was initially reached when the Celeron 300A was overclocked to 450Mhz and never climbing above that.


Hopefully, you now have a feel for what changes to your system will provide you with the most performance increase and generally how much it should cost. Also, if before reading this you weren't quite sure how overclocking was done, you now have a knowledge base to work from and hopefully enough confidence to give it a try. Faster graphics cards and bigger CPUs are the big two items in your PC that can give you more frags per second, or if you shoot like me, more feet per second to try and dodge those rockets! ;-)

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