NVIDIA GeForce DDR Roundup (March 00)

SDR versus DDR

Rather than having differences in the core itself, the DDR GeForce gains speed over the SDR GeForce in the way that it writes to the memory. SDR GeForce cards use the same technology that has been used in video cards in the past. Using this technology, the memory is written to one time per memory clock cycle. Thus, if the memory clock is set to run at 150 MHz, the effective memory clock speed is the MHz speed multiplied by the number of times written to per clock cycle, so in this case it would be 150 MHz x 1 for a total of 150 MHz on the memory clock.

DDR cards gain significant speed by writing to the memory twice per clock cycle. Rather than only writing on either the rising or falling edge of the cycle, DDR RAM can actually write at both these times. This results in an effective memory speed of twice the MHz rating that the memory clock is at. In this case, if the memory clock is running at 150 MHz, the total memory clock speed would be 150 MHz x 2, or 300 MHz effective.

This speed increase is important in the case of the GeForce because the 480 Million Pixels per Second that the GeForce processor is capable of displaying needs to get into and out of the memory as quickly as possible. Unlike TNT-2 cards, the GeForce places significant stress on the memory system. The resulting increase in memory clock speed also increases game speed, a fact most noticeable at high colors and resolutions. On average, DDR GeForce cards perform a maximum of 50% faster than SDR cards at the memory hungry resolution of 1024x768x32 in Quake III Arena. The differences, however, drop as resolution and color depth drop, meaning that at 800x600x16 the difference drops to 5% and at 640x480x16 there is no difference between SDR and DDR cards in Quake III Arena.

As is typical in the computer industry, the higher speed associated with DDR GeForce cards comes with a higher price. The question that remains is: where does this price increase come from and how is it justified? By looking at two GeForce cards, one SDR and one DDR, an unskilled eye would have problems distinguishing between the two. In fact, the reference design used is almost identical in both cards. The only visual clue that a specific card uses DDR RAM are slightly larger RAM chips and the placement of about two capacitors near each of these chips. Thus, it is evident that the board layout and design are not the factors driving up the price.

As can be deduced, the price increase in DDR cards is a result of the faster DDR RAM used on the card. However, the $50 price difference between SDR and DDR cards does not reflect how much more producing DDR RAM costs. In fact, when the numbers are crunched, DDR RAM chips cost about 3% more to manufacture than their SDR counterparts. So, how does a 3% increase in manufacturing costs result in a $50 increase in retail price? The answer is simple: demand.

This demand is reflected upon in two aspects. First, there is the demand placed on memory manufacturers by card manufacturers. The only producer of DDR RAM for use in video cards, Infineon, knows that they can charge more than an additional 3% for DDR RAM simply due to the fact that manufacturers are willing to pay more for it. Card manufacturers know that in order to have the fastest product on the market, DDR RAM will be needed, thus the demand placed on Infineon, as well as their stronghold on the DDR RAM market, allows them to make a hefty profit from DDR RAM sales. The second form of demand is that of the consumer. Card manufacturers know that a consumer who wants the fastest and best is willing to pay more for such a product. Thus, as long as DDR GeForce cards are king, card producers can hike up the price of the cards due to the fact that people are still going to buy them.

The question that remains is how long can this demand be placed on the market. Creative Labs and Leadtek think that they have an idea: not very long. Both companies, in anticipation of DDR card prices falling to the SDR level, have taken action to reflect this belief. Creative Labs stunned the industry when they announced that they would no longer be producing the SDR version of the popular 3D Blaster Annihilator. In addition, Leadtek has been quoted as saying that they soon will "be producing many more DDR cards than SDR ones." Both companies anticipate lower sales in SDR cards due to falling prices of DDR cards and thus feel justified reducing the availability of these cards.

With companies hinting at the death of the SDR GeForce, do they stand a chance in the long run? The answer is yet to be seen. In today's market, there is no question that the SDR GeForce is powerful enough to play current games. With the current level of 3D complexity found in games, the SDR GeForce will perform fine; however, the DDR GeForce excels at the higher colors and resolutions that gamers dream of. In addition, a retail price that reflects the 3% manufacturing increase would spell disaster for the SDR market. This outcome is becoming more of a possibility, especially with new processors slated to be released by NVIDIA. It is quite likely that the new NV15 chip will place the DDR GeForce in second place and thus lower its price down to SDR levels. If this were to occur, DDR GeForce cards would remain one of the cards to own while SDR GeForce cards would be almost obviated from the current gaming market. With this in mind, the price increase that one sees when comparing DDR GeForce cards to SDR GeForce cards is not only justified, it is well worth the premium.