Shootout - GeForce graphic cards

The first GeForce cards are available in numbers now. Good reason to take a closer look on some actual GeForce cards. Iīve tested the ELSA Erazor X, Guillemot 3D Prophet and ASUS AGP-V6600 Deluxe. All equiped with 32MB SD- or SGRAM and the 'oh so loved' NVIDIA GeForce 256 chip.

The main new features of the GeForce is the Hardware Transformation and lightning unit. NVIDIA calls it a GPU -  a Geometry Processing Unit. Thatīs also the Reason why the chip is called GeForce: 'Ge' for Geometry.
This specialized unit on the chip can make the transformation and light setup in hardware - this unburdens the system CPU. So it can handle a lot more triangles than before without loss of CPU power. Many developers are very pleased by hardware T&L because it allows to build much more complex and realistic worlds. The calculation of up to 8 lights in hardware is not as important as hardware T&L today.

But the main problem of these new features is that they are not supported automatic by all games. DirectX7 is needed and games must support hardware T&L explicit. It should be possible to patch DirectX games which use the standard DirectX transformation. But DirectX transformation was very slow in the past and most developers used their own transformation algorithms. That may also be the reason why there are only very few T&L patches for games until now. OpenGL is a different situation. This 3D API has its sources in the workstation area around SGI & co. Hardware geometry acceleration is an old shoe here. Thatīs why OpenGL games based on the GLQuake, Quake2 and Quake3 engine can take much profit of the GeForce T&L unit.

But there are a lot more new features in GeForce. It has a much higher fillrate than a TNT2 Ultra (300 to 480MPixel/sec) and can render 4 pixel per clock (TNT/TNT2: 2) or 2 when using multi-texturing. The chip also supports Dot3 Bump Mapping in hardware. TNT and TNT2 could only do emboss bump mapping in software - this was slow and didīnt look very nice. Another nice feature is Cube Environmental Mapping which allows spherical reflections. The reflection maps can also be created dynamicly but this pretty slow today.
Vertex blending - thatīs a sophisticated technique that allowing game developers to create smooth joints between the multiple parts of a geometric model. This can be used for example for better character animations.

Tere are a lot more features in GeForce. But this were the most important since there are no real soltutions for others today, like mainboards that use stuff like AGP 4X etc.

	Dynamic Cube Environmental Mapping	The Wole Experience (T&L): 22 additional WXP Screenshots
Dot3 Bump Mapping

real HW-Monitoring by ASUS

Hardware Monitoring: You may allready know this from maninboards. It means that you can control parameters of your graphics card. ELSA uses the ChipGuard technology to control the temperature of the GeForce chip. It  clocks the chip down when it reaches a critical temperature. ASUS makes a larger step and puts a Winbond hardware monitor chip on the V6600 Deluxe. The ASUS SmartDoctor sofware  controls temperature, voltage and fan rotation speed of the card. More about these features later.

Clockspeeds

You may be suprised when you read the specs of GeForce cards. Chip and memory are using pretty moderate clockspeeds of 120MHz core- and 166MHz memclock. The memclock in special is very low compared to TNT2 Ultra cards which use 183MHz or more. I asked ASUS about that an got an interresting explanation: High memory clockspeeds are not a problem of the memory chips itself but of the clockgenerator that is included in the GeForce chip. The chip gets more hot because it has to access the memory much more often.
The GeForce with its huge amount of transistors gets already pretty hot at normal clockrates - thatīs the reason why no faster clockspeeds are used for the memory.

The only help besides of overclocking is the use of cards with DDR (Double Data Rate) memory. This memory runs with real 150MHz but it transfers data on the high and low peak of the clocksignal. So you get effective 300MHz clockspeed. DDR cards are a lot faster at higher resolutions than the SDRAM or SGRAM cards that are available today. DDR cards will arrive the market in mid of december.

Copyright: RIVA Station 1999 - Lars Weinand
No Copy without Permission!

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