NVIDIA GeForce SDR Roundup (February 00)

While the GeForce GPU only comes in one type, the memory type used on GeForce cards actually come in two varieties: SDR and DDR RAM chips. SDR, the RAM type examined in this roundup, stands for Single Data Rate. This means that for every clock cycle, the RAM is written to once. The RAM found in SDR cards can be SDRAM or SGRAM, with the vast majority of manufacturers using EliteMT SDRAM chips (ELSA uses SAMSUNG SDRAM chips). DDR RAM, standing for Double Data Rate, is used in cards that generally cost $50 more than their SDR counterparts. DDR RAM can actually write to the RAM twice per clock cycle, on the rising and falling edge of the cycle. This provides a speed increase in the memory bus, as the RAM runs at 150 MHz x 2 resulting in a 300 MHz memory clock speed.

Due to the similarities between SDR and DDR cards, AnandTech has actually found that some manufacturers are phasing out the SDR versions of their cards completely. Creative stated phasing out rather early in the game, and the SDR version of their popular 3D Blaster Annihilator card is almost impossible to find now because Creative does not produce it any more. We have also gotten word from Leadtek that they will soon "be producing many more DDR cards than SDR ones". The reason for this is two fold. First, due to the fact that the reference design for SDR cards is very similar to that of DDR cards, manufacturers can make the transition from using SDR to DDR RAM rather easily. Secondly is the cost of DDR RAM. From the chip manufacturer's view, DDR RAM costs only about 3% more to make than conventional SDR RAM. Due to the high demand of DDR RAM, the RAM producers are actually selling the chips at a higher premium. Card manufacturers, in anticipation of DDR RAM price dropping to 3% more than SDR RAM, have stated phasing out SDR cards to make way for better performing DDR cards at less cost.

While SDR cards are still prominent in the market, DDR GeForce cards are not an option for some people due to the higher price tag. The fact of the matter is that the only difference between DDR GeForce cards and SDR GeForce cards is the type of RAM used and the position of about 2 capacitors near each RAM chip. The processors are not different, the cooling system remains the same, and the reference design does not change significantly. For many people, the added speed increase with a DDR GeForce card will not be noticed under normal gaming, thus making the less expensive SDR model a better choice.