Graphics Cards: Closer Look

We had two GeForce3 based graphics cards at our disposal: GV-GF33000DF from Gigabyte and PixelView XX-Player from Prolink:

Gigabyte GA-GF3000DF

PixelView XX-Player

Gigabyte was one of the first to announce its GeForce3 based solution. The card carefully follows the reference design and features Gigabyte's brand blue color PCB:

GV-GF3000DF features a DVI-Out and S-Video Out located on the GA-GF2TV daughter card:

GV-GF3000DF is equipped with 64MB local graphics memory. There are 8 3.8ns chips by EliteMT onboard. The working frequency of this memory makes 460MHz (230MHz DDR):

By the way, NVIDIA's reference design implies that there may be a TV-coder microchip on the main PCB as well as on the daughter card. In our case the Bt868KRF TV coder from Conexant is installed onto the daughter card.

The reverse side of the graphics card is provided with the core and memory power supply microchips. By the by, GeForce3 core seems to be consuming very little power because there are no powerful transistors on the card. Also the reverse side of the PCB has Sil164CT64 chip from Silicon Image, which is responsible for coding and transferring of the video signal to the DVI interface.

The chip is cooled down by an active cooler, but there is so little room between the chip and the fan that its effort seems to be wasted:

That is why we would regard it as passive cooling, actually, rather than active. Fortunately, the holes in the PCB, provided by the reference design allow installing such coolers as Blue Orb, for instance, which is exactly what we did right away. Nevertheless, the cooler didn't matter that much, because the graphics card didn't get overheated and didn't crash when working with the Blue Orb cooler installed as well as with its own original cooler.

Prolink PixelView XX-Player card is also based on the reference design from NVIDIA and differs from GV-GF3000DF by the absence of a DVI-Out, and by the location of the TV-coder, which is situated on the main PCB and not on the daughter card like by GV-GF3000DF.

The card from Prolink we had at our disposal was equipped with the same memory chips as Gigabyte GV-GF3000DF, although their working frequency was lower: only 400MHz (200MHz DDR):

When we tried to set the memory frequency equal to 460MHz, the card worked fine throughout all the tests and we didn't discover any problems. We suspect that the default frequency was set lower because this Prolink PixelView XX-Player was a preproduction sample, so the mass pieces may have higher memory frequency.

Testbed

To test our cards we used the following system:

• AMD Athlon 1200MHz CPU (133MHz FSB);
• ABIT KT7A (VIA KT133A) mainboard;
• 256MB NCP PC133 SDRAM;
• Fujitsu MPE3084AE 8.4GB HDD.

Software:

• Windows 98 SE build 4.10.2222 A;
• DirectX8.0a;
• Quake 3 Arena v1.27;
• Unreal Tournament v4.36;
• 3DMark2001 build 200.

Drivers:

• Detonator 10.80 for NVIDIA GeForce2 Pro and GeForce2 Ultra based graphics cards;
• Detonator 11.01,12.00 for NVIDIA GeForce3 based graphics cards;
• 8.13.7089 for ATI RADEON DDR 64MB VIVO.

Testing Method

In our review we will compare the results obtained for GeForce3 (represented by Gigabyte GV-GF3000DF) with those obtained for ATI RADEON 64MB DDR VIVO, Creative 3D Blaster Annihilator 2 Ultra (NVIDIA GeForce2 Ultra) and ASUS V7700 64MB (NVIDIA GeForce2 Pro), having set its core to 200MHz and overclocked the memory up to 230MHz (460MHz DDR), which is the working frequencies of NVIDIA GeForce3.

When testing in Quake3 Arena we set the textures and the level of detail to the maximum, enabled trilinear filtering. All other settings were left as default. The tests were run in demo127.dem, which is included into the 127g point release patch.

In Unreal Tournament we set the textures and objects to the maximum, enabled trilinear filtering. All other settings were default. The tests were run in utbench.dem.

The tests in 3DMark2001 were run with all default settings. For 16bit modes we enabled 16bit textures and 16bit Z-buffer, while for 32bit modes - 32bit textures and 24bit Z-buffer.

Overclocking and Architecture Bottlenecks

In order to figure out how well-balanced the graphics cards based on NVIDIA GeForce3 chip were, we measured their performance in Quake3 Arena with the core and memory frequencies slightly increased and decreased. On the graphs below the horizontal axis indicates the memory frequency, and the colored curves correspond to different core frequencies:

You can see that the performance of GeForce3 in 16bit mode is much more dependent on the core clock frequency than on the memory frequency. In 32bit modes the performance increases almost in the same way for both: memory and core overclocking.

These results show that very soon we may see the first "Ultra" modifications of GeForce3 graphics cards, since the increase in the core clock frequency stimulates the growth of the graphics card performance.

We managed to achieve the maximum of 225MHz core and 480MHz memory frequency for Gigabyte GV-GF3000DF. Prolink PixelView XX-Player managed to work at 240MHz core and 500MHz memory frequency.

By the way, when we overclocked the core of PixelView XX-Player up to 246MHz, we noticed that some blocks simply fell out of the scenes:

These regularly located blocks with the size of 8x4 pixels allowed us to see the objects located behind them, when they fell out. They are most likely to appear as a result of incorrect work of the core during overclocking and prove our supposition about the "low-resolution Z-buffer" being cached in the chip core. Another indirect evidence is the fact that caches are usually the first ones to crash if the overclocked core gets overheated, because caches are local overheating centers. When we set the core frequency equal to 247MHz, the scene covered with the "missed-blocks-ripples" very quickly and then the system crashed.

Test Results: Quake3 Arena

Due to HSR, unusual memory architecture and probably also textures caching, GeForce3 turned out an indisputable leader at high resolutions in 32bit color mode. On the other hand, it is quite interesting that in 16bit color mode GeForce3 based graphics cards fell behind GeForce2 Pro overclocked up to the level of GeForce3. How could we explain it? GeForce3 core may be performing some operations, calculations connected with determining the objects visibility, however the OverDraw value of the tested scene isn't high enough for the performance gain provided by HSR to make up for the resources spent on these calculations. Besides, it is also noticeable that in 16bit modes of this test the memory bus bandwidth isn't a bottleneck at all and hence the HSR shouldn't provide any serious gain here.

Test Results: Unreal Tournament

Since the gaming engine in Unreal Tournament is optimized in a very specific way, the gaming performance depends a lot on the overall system fastness. GeForce3 proved just excellent in 32bit mode, however, in 16bit mode it again fell behind GeForce2 Pro overclocked to the frequencies of GeForce3. The lag at 800x600 made 2.6%, at 1024x768 - 3.2% and at 1280x1024 - 2.2%. Taking into account errors in measurements, the lag may be considered the same for all three resolutions. It is probably the HSR calculations carried out by GeForce3, which tell on the performance. In 32bit modes, especially at higher resolutions, the memory bandwidth starts limiting the accelerator's performance and this is where GeForce3 overtakes everybody.