The cards
We have a pair of 6200 cards to review. The first has a single 16MB DRAM chip onboard with a 32-bit path to RAM, and the second has two chips, for 32MB and a 64-bit data path.

The GeForce 6200 with TurboCache

A single RAM chip peeking out from beneath the passive heat sink

The only cosmetic difference between the two cards is the second RAM chip populating a pad on the back side of the 32MB card.

Test notes
The tests on the following pages were intended to stress the TurboCache scheme. We wanted to see how the 6200 with TurboCache would perform with lots of accesses to main memory, so we chose to test new games at higher quality settings with lots big textures. We also wanted to test some of the theories about shader effects reducing bandwidth pressure, so we tested some scenarios where shader effects are rather intensive. In short, we tested the GeForce 6200 with TurboCache much like a mid-range graphics card. We believe that's a fair thing to do, in part because the latest games tend to look better at their highest quality settings at lower display resolutions than they do at higher resolutions and lower quality settings.

We've included an expected rival to the 6200 with TurboCache, the Radeon X300 with 128MB of local frame buffer memory behind a 128-bit data path. We've also included a graphics solution from ATI that's very similar to the 6200 with TurboCache: the Radeon Xpress 200 IGP. Like the 6200, the Radeon Xpress 200's integrated graphics solution uses 16MB or 32MB of local memory in addition to system memory. The IGP can interleave accesses to system memory and local memory in order to get more total effective bandwidth.

However, we have to acknowledge that the Radeon Xpress 200 is overmatched here. It has only two pixel pipelines running at up to 350MHz core clock speeds (actual configs may vary), and it has no real vertex engines, relying on the CPU to do most of that work. Also, the motherboard we're testing has only 16MB of local memory onboard, so it's less than optimal. We configured that board to use coarse-grained interleaving between local RAM and system RAM in order to achieve a total of 144MB of memory allocated to graphics. ATI recommends fine-grained interleaving for optimal performance, but that would limit us to 32MB of total graphics RAM—not enough.

Still, the Radeon Xpress 200 should serve as an able stand-in for chipset-based graphics solutions, because it is the very best chipset-based graphics processor on the market today. We've already see the Xpress 200 IGP outperform the GMA 900 graphics processor in Intel's 915G chipset. We should be able to get some sense from these results how a TurboCache solution compares to a chipset-based IGP.

Finally, we have used more conservative memory timings in our test system than usual, because we wanted to be realistic in testing TurboCache performance. Most consumer PCs are sold with low-grade memory that runs at relaxed timings. We've chosen 2.5-3-3 at 400MHz as a reasonably representative set of timings. Running 2-2-2 RAM would have given the 6200 with TurboCache an advantage over the typical system in which it will likely be deployed.