Apr30

Written by:Pete Leoni
Sunday, April 30, 2000 6:00 PM

Anyone who has had to fool with audio cards knows that compatibility is a real consideraion when putting together an audio computer. Clearly, the Intel processors are the benchmark for compatibility. What are the viable options then?

1. The PIII Coppermine FCPGA "EB" which runs on the 133 Mhz bus and a Motherboard using the VIA Apollo 133 Mhz chipset.
2. The PIII Coppermine FCPGA "E" which runs on the 100 mhz bus and may be successfully overclocked using the Via Apollo chipset at 133 Mhz bus speed
3. The PIII Coppermine FCPGA "E" running on the venerable BX chipset, which is also capable of being overclocked on the 133 Mhz bus.
4. The new Celeron Coppermine FCPGA (AKA "The Celermine") which natively runs at 66 Mhz FSB but may successfully be overclocked to 100 MHz FSB on appropriate motherboards using the Intel BX (or VIA Apollo) chipsets

CPUs: The Issues

1. The PIII Coppermine "EB" chip is made to run natively at 133 FSB. We have already established that the Intel i820 motherboards that Intel intended to be used for this CPU are not suitable because of expensive memory requirements and/or poor or faulty performance in general. Another consideration here is the cost of the chip itself. At the time of this writing an Intel PIII chip at 850 Mhz (our nominal CPU speed goal) costs around $800!

Those of us who built the first "Roll Your Own" computer know by now that we don't have to spend that kind of money to get high audio performance. We know a few tricks! Right off the bat we can rule out Intel CPU's made to run natively at 800 Mhz or better, simply on financial grounds.

2. The Coppermine PIII "E" chips. These are identical to the Intel PIII "EB" chips with one exception. They are made to be run natively at 100 Mhz FSB, so they may be overclocked by using the 133 Mhz FSB. Therefore it would seem to be viable to purchase a low cost 600 Mhz chip and run it at 800 Mhz at 133 FSB.

But here we run into a problem or two. As we have established, Intel does not have a decent or affordable chipset which is designed to run at 133 MHz, so we will be forced to either overclock the venerable BX chipset, a chipset that was never designed to be run at 133 mhz, or use the VIA Apollo chipset. Remember, both the Intel i820, and the Via Apollo chipsets have reduced memory performance when compared to the venerable BX chipset.

It would seem the ideal situation would be to run the BX at 133 MHz. If we chose to overclock the BX chipset, there are several motherboards available, such as the MSI BX- Master which will have great memory performance, and can be run at 133 FSB, but we will still run into one big issue. There is no way to run an AGP video card within specifications using the BX chipset at 133 Mhz, therefore we must either use a PCI video card or find an AGP video card which is happy to run in an overclocked state. Both of these solutions are certainly viable and I have used them both in my DAW designs, but again, for the purposes of this article I prefer to keep things as simple and foolproof as possible

Celeron To the Rescue (Again)!

I don't know if Intel just loves musicians or, maybe the "Cyber Gods" are rewarding us for living good clean lives (not!), but once again Intel has given us a quite a gift with the new Coppermine-based Celeron.

As most of us know by now "Coppermine" Is Intel's name for it's newest .18 micron CPU core. Both the PIII Coppermine and the Celeron Coppermine now include Intel's SIMD instruction set, a real plus these days as many apps are now optimized for these instructions. Like the original Celeron "A" chips the new Coppermine chips (Both Celeron and PIII) use on-die L2 Cache which runs at system CPU speed instead of a fraction of CPU speed as in the case of earlier PII's PIII's and current Athlon chips. As many of you know by now, for audio a fast L2 cache is highly desirable, In fact the speed of the L2 cache is arguably more important that the size of the cache in audio applications. Why am I making this point? Here are the facts:

There are only two primary differences between the expensive PIII Coppermine Chip, and the affordable Celeron Coppermine chips. On the PIII, there is 256K of onboard L2 cache, On the Celeron there is 128K. Difference number two is simply Intel intends the PIII's to be run at 100, or 133 FSB and intends the Celeron version of this chip to be run at 66 mhz FSB. You will notice that I said "intends" As you may have already guessed by now, we aren't going do things the way Intel intends!

When I wrote the first "Roll Your Own" article, the subject of overclocking a CPU was a lot more controversial than it is now. Things have changed since then, and overclocking has become almost mainstream. We have even seen even the Wall Street Journal cover this issue! With so many overclocked units functioning perfectly in the field for years now, and with many resellers offering pre-tested and guaranteed overclocked CPU's, I am going to base this DAW Recipe on a particular, and highly overclockable Intel Chip, the Celeron 566.

Get Your Kicks With a 566

With every new CPU core that is produced, there is a top speed a core is capable of and a "sweet spot". In the case of the .18 micron Coppermine core the top speed seems to be about 1000 Mhz (1 Gigahertz). As most of you know by now, Intel is selling Coppermine chips at 1000 Mhz. Getting that speed out of the Coppermine core is not easy even for Intel. In fact, Intel uses large heatsinks and higher core voltages to achieve these speeds. If that sounds like Intel itself is using overclocking techniques to squeeze 1 Gigahertz out of the Coppermine core, it's because that is precisely the case!

At the time of this writing an Intel CPU running at 1 GHz costs over $1300! Instead of paying that kind of cash, we are going to use the Celeron 566 overclocked to 850 Mhz on the BX chipset at 100 MHz FSB. I feel this configuration hits the Coppermine's price / performance "Sweet spot" and will give us about 85% of the performance at about 20% of the cost.

We like that.

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