Overclocking the TNT

125MPH in a 110MPH Zone

That was the problem with the original tests, if you notice the results overclocking the Canopus Spectra 2500 produced, the performance barrier seemed to be at around the 110MHz limit.  The 20MHz increase in clock speed resulted in a tremendous 13% performance increase, however bumping the clock speed up to 125MHz, a full 15MHz increase in clock speed, only resulted in a 20% improvement over the scores at the default 90MHz clock speed, and a meager 7% increase over the scores at 110MHz. 

The reason?  The memory clock of the TNT card remained at 110MHz, the default set forth and recommended by nVidia.  By overclocking the chip to a level above 110MHz we were essentially ruining the balance of power between the speed at which the TNT can process the data and the speed at which the RAM can retrieve it.  Normally, with the TNT clocked at 90MHz and the memory clocked at 110MHz, the TNT can process all geometry data and retrieve data from the local [graphics] memory in an efficient manner.  When the overclocking was performed, the speed of the processor was increased, without compensating for this performance increase by upping the clock speed of the memory.  This explains the diminishing returns once the TNT's clock speed surpassed the speed of the memory. 

Removing the Bottleneck

With the memory clock established as the bottleneck in this case, what is there left to do than remove it?  That is easier said than done.  When the TNT is released at full speed in February of next year you can expect it to ship with considerably faster SDRAM or even SGRAM depending on the cost of the chips at the time of production.  While the actual clock speed may vary, we should be able to expect that the memory will run at a speed considerably greater than 125MHz, therefore eliminating the bottleneck we just discussed.  Unfortunately, the availability of such high speed SDRAM is close to nothing for the price point most TNT cards will be selling for, meaning it is unlikely that we'll be able to overclock the RAM on most TNT cards too far beyond the recommended levels.