Can you talk to us about certain yields at certain speeds and how and why this is done? Is it really beneficial to the end-user or is it just essential to validate the warranty?
Steve Mosher: "Sorry for the long answer. I cannot talk about specific yield figures for any of my supplier's parts, but this much is clear. You generally don't speed bin parts unless it makes economic sense. That means your yield has to be worth the engineering effort and you have to be able to keep the market supplied.
How and why is this done? The how is fairly simple. Every part that is created by a chip vendor goes through various testing procedures. Simplistically, the chip is put on a test machine and certain functional tests are run to make sure that the chip operates as designed. The chip is also tested for its operating frequency.
So let us assume you designed a chip to run at 143MHz. As chips come off the product line they are tested. Let's assume that 90% pass at 143MHz. Then you have to characterize the chips and see how much faster than 143MHz they can run. You might find out that you have a good yield at 183MHz, so you create three products. Chips that pass the tester at 183, those that pass at 166 and those that pass at 143. Now Nvidia and 3dfx didn't invent this process of speed binning. Intel does it. Memory guys do it. WHY do silicon vendors do it? Well, it is the simplest way to create multiple products. The fastest parts command a premium (price) because they are more scarce, the mid-range parts are priced at a smaller premium and the slowest parts are the cheapest. So instead of engineering three chips, they engineer one chip and sort it into three speed bins, and they charge more for the faster ones.
Is speed binning beneficial to the end user? Its tough to make blanket statements about what is beneficial to end-users. In the end the benefit is in the eye of the beholder. But one thing is clear, there has to be a symbiosis between the high end and the low end. To yield the 183MHz part you must build and sell the 143MHz part. Since the high frequency parts are typically less than 50% yield, somebody needs to buy the slower parts. This is the main reason why end users will have to wait for the voodoo3 3500. In order to yield a big enough quantity of v3500, 3dfx needs to build a lot of v3 2000 and v3 3000 to yield enough v3 3500. Simply put, you can't sell the high end without selling the low end too.
I hope this helps."
Steve Mosher
Vice President, Graphics Business
Creative Labs, Inc