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Video processor G71The battle for technology leadership crown between NVIDIA and ATI is not standing still for a minute, although most part of the battle is behind the scenes for the ordinary buyer. Announcements of new VPUs occur normally once every six months, and all this time the companies work very hard at new technologies, architectures processes, etc. After presentation its video chip R580 and X1900 series video cards on its base in January, ATI rightfully took over the honorable title of a manufacturer of the world's fastest video cards. Certainly, since then all the computer community has been waiting for reciprocal move from NVIDIA. We remember the history of opposition between GeForce 7800GTX and X1800XT. The former was released last summer, and the latter - only in autumn. The performance of these two video cards is matching enough, but ATI's product showed a slight superiority. That time, to keep the leadership crown at speed, NVIDIA made a simple move through releasing the overclocked version 7800GTX which was equipped with the most powerful cooling system and super-fast memory. A trick like that was very hard for NVIDIA to repeat in January after the release of ATI X1900 because the frequency rise potentials of G70 made following the 110-nm process technology was exhausted, and the stocks of overclocking-friendly chips came to an end. That time, we wondered what the reciprocal move from NVIDIA would be like. Would that be a new core based on a new architecture, or how many pipelines would that offer? It is an extremely challenging task to overcome R580 having 48 pixel pipelines. Or, perhaps that would be a new-generation chip, say, G80? Now we can state with confidence - NVIDIA's new chip is dubbed G71 and, frankly, it can't be regarded as a novelty. In fact, we get some re-styling of the well-known G70 architecture which has moved to the 90-nm process technology. Let's see what the G71 is like. 
This is how the new NVIDIA's VPU looks like. Interestingly, it has already been the second revision of the G71 chip. The chip was produced on the 5th week of year 2006. Due to the migration to a finer process technology, the chip area has shrunk essentially. To give a better demonstration of the difference, we are bringing in a joint photo with the G70 chip. 
On the photo, you can see the G70 (to the left) installed into the 7800GTX 512 video card, and G71 (to the right). These two chips make a big difference from one another by the exterior. The difference in the core size, as I have already mentioned, is caused by the different process technologies - 110 and 90 nm, respectively. G71 also lacks a limiting frame over the substrate perimeter, which is designed to prevents the core chip from damages. To all appearances, the scrap rate caused by incorrect fitting of coolers has proved to be negligible (or missing at all), so they decided to save on the frame. Another thing of note is the small letter "U" in the marking, which suggests preliminary selection of the most overclocking-friendly G71 chips, like it was with the video card 7800GTX 512. Nevertheless, the incident with disappearance of 7800GTX 512 from the retail is unlikely to repeat for GeForce 7900GTX. NVIDIA's migration to the 90-nm process technology which started with the G72 core (video card on the base of 7300GS) has proved successful. Long before the announcement of NVIDIA's new video processor, there were rumors about the increased number of pixel pipelines. Numerous sources assumed that to battle the 48 pixel pipelines of R580 NVIDIA would increase the number of pipelines. However, that hasn't come true. The formula has remained as before - 24 pixel pipelines and 8 vertex pipelines. As many as there were in the predecessor - G70. Of course, migration to the fine process technology favored to the rise of operating frequencies. The nominal operating frequency of 7900GTX chip has been set to 650 MHz. As they say, just feel the difference as compared to the standard 430 MHz for 7800GTX. In terms of dry figures, the boost is 51%. But in simple terms, it is by more than 1.5 times. Even as compared to the frequencies of 7800GTX 512, the boost is essential. Despite the architectural kinship, G70 and G71 do make a difference. However strange it seems, the novelty offers fewer transistors - 279 mln versus 302 in G70. You can only guess what caused such "weight loss" since functionally it hasn't turned worse - even contrary to that. Now each of the two integrated DVI outputs offers support for the DualLink technology and allows enjoying picture at resolutions up to 2560x1600 inclusive. As a joke, we say that in G71 NVIDIA has got rid of those transistors which restricted the frequency rise capabilities. :) 7900GTXLet's see what 7900GTX looks like. That's just the current top-end is dubbed in NVIDIA's video card product line. 
As you see, GeForce 7900GTX externally looks identical to GeForce 7800GTX 512. The major part in that is played by the cooling system which we have already seen in 7800GTX 512. 
At first glance, use of such powerful cooling seems to be somehow excessive. The thing is, the chip G71 despite its high clock speed features in quite moderate appetites for power consumption. Perhaps, installation of such a cooler is more likely to be a marketing move - the "hi-end has got to be known personally", but a cooler like that is difficult to miss. From the user's viewpoint, that offers more advantages than shortcomings. On the credit side of 7900GTX, there is a completely noiseless operation even under load (the cooler rotates at a constant speed), high efficiency of the heat-sink, and a superb overclocking capability. Of the shortcomings, it is the dual-slot make. But that is unlikely to be a shortcoming for hi-end systems. It's quite probable that in future we'll see a wider spectrum of coolers fitted on 7900GTX, but that will be a real challenge to offer as efficient solution as the nominal cooler. 
As you may have noticed, the reverse side of the PCB is fully identical to the PCB of 7800GTX 512. This suggests that the contact layout in the new chip G71 coincides with that for G71. Hence, in theory we can expect emergence of video cards on the PCB of 7800GTX with a single-slot cooling system. We can only guess if such an interim version will appear or not. 
On removing the cooler, we see that the front side of the PCB as well is fully identical to the PCB of 7800GTX 512. There are some minor differences in the number of components, but they once again prove the smaller power consumption of the new video processor. In the power supply subsystem of the video card on top, a few components have not been unsoldered. Another difference is in that the reference video card lacks the Philips 7115 chip which used to be in charge of the video capture. Once we receive production samples of the video cards, we'll find out if the decision to give up video capture codes was NVIDIA's or if that is a feature of reference video cards. As was expected, by analogy with 7800GTX 512 the video card 7900GTX offers 512 MB video memory onboard assembled of 8 chips positioned on the front side of the PCB. 
The access time is 1.1 ns, which is equivalent to the nominal 1800 MHz DDR. As we remember, 7800GTX 512 used the same video memory, and its operating frequency equaled to 1700 MHz DDR. In the case of 7900GTX, the memory frequency is even lower - "merely" 1600 MHz DDR. However, its efficient cooling system coupled with the reduced GPU power consumption allows running easily at the nominal 1800 MHz DDR. Needless to say that the memory bus is 256 bit wide, which is evident. By the general impression, we can say that the GPU is evidently aimed at the minimum production cost. On the other hand, the video card itself offers all the attributes of a top-end product - powerful cooling, extremely fast video memory with quite a margin for speed. Despite such "image-making" luxuries, the recommended price for NVIDIA's new flagship is much lower than in the predecessor - merely $499 versus $649 in 7800GTX 512. Of course, even five hundred dollars is not little for a single video card, but the trend is indeed rejoicing after the old ways when after exorbitant swelling of prices for top-end products they gradually go down. In other words - the "entrance tickets" to the enthusiasts' community have turned cheaper. Who knows, maybe the number of enthusiasts will go up through that. Very soon we'll find out how real retail prices will be different from the recommended. 7900GTX video cards are already widely available on sale and soon should arrive in Russia as well. Next 
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