Nvidia GeForce 6200 TurboCache: Fast Name, Slower Speed

Nvidia GeForce 6200 TurboCache

While the normal GeForce 6200 is based on the NV43 graphics processor (GeForce 6600) with four of the eight pixel pipelines as well as the "Color Compression" feature deactivated, Nvidia actually created a new processor (NV44) for the GeForce 6200 TurboCache. To keep the transistor count down, the NV44 only has four pixel pipelines to begin with. Like the NV43, this processor also comes with three vertex shaders, but only two ROPs (Raster Operation Pipes) instead of four. However, cutting this corner has a huge negative impact on memory access times. Yet these aren't the only differences between the standard GeForce 6200 (NV43) and the new GeForce 6200 TC cards (NV44).

The "TC" abbreviation appended to the model number stands for TurboCache. Of course, despite what the name implies, this processor is in no way turbocharged, nor does it sport any integrated caches or embedded-DRAM. Instead, following the low-cost mantra that "less is more," there is still less to cards based on this processor - namely less local video memory. Indeed, "TurboCache" is a prime example of vacuous and exaggerated market-speak names.

Nvidia's GeForce 6200 TurboCache cards only sport very little local memory, namely either 16, 32 or 64 MB. This is nowhere near enough for modern 3D applications. To make up for this shortcoming, the card draws upon the PC's main memory. The new, very fast PCI Express bus is supposed to supply the necessary bandwidth. Nonetheless, this solution isn't exactly fast - compared to the memory bandwidth offered by enthusiast-level graphics cards, the bandwidth available through PCI Express can only be considered puny.

For example, a GeForce 6800 Ultra can transfer a full 36.5 GB/s over its 256 Bit memory bus. In contrast, PCI Express offers a peak transfer rate of 4 GB/s. While this is still twice as fast as the AGP 8x bus, it is positively lame by comparison and certainly does not represent a "turbo" speed. Additionally, bear in mind that a video card has exclusive access to its local, on-board memory. Compare that to the PC's main memory, which already has to divide its bandwidth between the CPU and running applications, and you can see that there won't be much left for the graphics card.

Nvidia has defined three GeForce 6200 TurboCache variants, which differ in the amount of local memory with which they come equipped:

1. GeForce 6200 TurboCache 16-TC/128 MB, $79 - 16 MB of local memory (32 Bit) on-board. Additionally, the card can address up to 112 MB of system memory. Clock speeds: 350 MHz core, 700 MHz (DDR) memory.
2. GeForce 6200 TurboCache 32-TC/128 MB, $99 - 32 MB of local memory (64 Bit) on-board. Additionally, the card can address up to 96 MB of system memory. Clock speeds: 350 MHz core, 700 MHz (DDR) memory.
3. GeForce 6200 TurboCache 64-TC/256 MB, $129 - 64 MB of local memory (64 Bit) on-board. Additionally, the card can address up to 192 MB of system memory. Clock speeds: 350 MHz core, 550 MHz (DDR) memory.