The cards
The first card based on the G80, the GeForce 8800 GTX, requires a power supply of 450 Watts, while NVIDIA mentions figures of 750 to 1000 Watts for configurations with 2 cards in SLI! This GeForce 8800 GTX features a GPU clocked at 575 MHz (the processor shaders are clocked at 1350 MHz) and 384 bit memory at 900 MHz, which provides a comfortable bandwidth. You will have to pay a little bit more than 650€ to acquire this 27 cm / 10.6" long beast that requires the use of two power supply connectors. Noise is very low, just a bit higher than the GeForce 7900 GTX, which is our reference.
The second card, the GeForce 8800 GTS uses a GPU with restricted capacities. The number of processor shaders decreases from 128 to 96 and the number of texturing units from 32 to 24. The GPU frequency decreases to 500 MHz (1200 MHz for the shaders' processor) and the memory to 800 MHz but this time in 320 bits. Calculation resources are reduced by 33% and the bandwidth by 25%. Price will also be lowered to 450€ - 500€. The cooling system is similar to the higher end model and is simply shorter. This card is also very silent.
This GeForce 8800 GTS was provided by Galaxy. We thank the company for sending it so quickly. As NVIDIA only builds a few graphic cards, they are all identical and partners do not have many options to make their products stand out, at least in the beginning. Galaxy told us that the next GeForce 8800 GTX would be equipped with a water-cooling solution designed by Zalman.
Finally, Asus sent us a second 8800 GTX and a GTS. Thanks to these cards we were able to test them in SLI.
We noted that each GeForce 8800 has a companion chip, the NVIO (on the left). It handles video input and output. We don't know really why NVIDIA chose this solution which is more expensive than a simple GPU integration. Maybe to have easier evolutions without having to build a new GPU? Maybe to avoid having to buy Silicon Image chips?
For the PCB, there is an interesting detail. The GeForce 8800 GTS, even if they feature 640 MB of memory (at 320 bits), can sometimes have 768 MB of memory even if some of this memory is unused. Maybe the reason is that it is easier to build a single PCB with every memory space occupied rather than a different version for each ROPs that has been deactivated (since of course, it isn't always the same that poses a problem or is deactivated).
Consumption
The power consumption of these graphic cards was evaluated with measurements taken directly at the power outlet. This represents the computer’s entire power consumption, with an Enermax 535W. Figures were obtained under Window’s desktop and in use with a fillrate test that saturates the pixel shader with Prime95 and with 3DMark05 (GameTest 3) also with Prime95. Prime95 makes it possible to have constant CPU usage regardless of a graphic card’s performance.
We have to say that we worried too much about the power consumption of the GeForce 8800 GTX. In practice, it has in fact approximately the same power consumption as the ATI Radeon X1950 XTX. In 2D, however, the GeForce 8 required much more power than the other cards. Finally, NVIDIA’s new architecture more easily avoids feeding power to unused circuits. This is shown by our shader that only saturates the mathematical units of the chip. Under these circumstances, power consumption of the GeForce 7 increases compared to 3DMark, whereas it diminishes in the case of the GeForce 8.
