Volari Dual-Chip Cards
XGI has chosen a very special design to be able to compete with such strong rivals as NVIDIA and ATi. Instead of designing a complex new DirectX 9 part that would be very expensive to produce due to the high transistor count it would require, XGI instead chose to simply use two chips on its Volari Duo cards.
The problem that chip designers face is that higher transistor count means greater chip-size and, consequently, fewer chips per wafer. Also, the number of faulty chips per wafer increases. This in turn drives up the production costs for complex chips, such as ATi’s R360 (ca. 110 million transistors) or NVIDIA’s NV35/38 (130 million transistors. In the end, these chips are more than twice as expensive to produce as those that count only about 80 million transistors - such as the mainstream RV360 and NV36. And, of course, the Volari V8.
Dual chip solutions are not new by any means. 3D graphics pioneer 3dfx had already presented such a design with its Voodoo 5 line. ATi also experimented with a two-chip design back with the Rage Fury Maxx. Obviously, the combination of two chips sounds very tempting, since theoretically the result should be twice the power with only minimal effort. Just as obviously, if it were that easy, everyone would be doing it, right ?
Indeed, there are some disadvantages to the approach. The first one relates to the memory. Each chip requires its own frame buffer, meaning that twice the amount of memory needs to be used on such a card as on a conventional design. In effect, a Volari Duo with 256 MB of memory really only offers 128 MB of usable memory.
The second problem has to do with controlling the graphics processors. The AGP bus is only capable of accessing one graphics chip, so the second chip has to be "hidden" from it. ATi’s solution to this problem for the Rage Fury Maxx was to integrate an AGP-to-PCI bridge into the card. While this worked, the inherent disadvantage was that the card would only work up to AGP 2X.
XGI has come up with another solution. In their design, a "master" GPU communicates directly with the CPU. The second GPU, the "slave," communicates with its the primary chip via the so-called BitFluent bus. To this end, a special bridge is integrated into the chips.
The third disadvantage has to do with the complexity of the overall design. It requires more power and a more complex PCB (a dual cooling solution, dual power supply, more traces on the PCB). It is this greater complexity that usually makes dual-chip designs rather unattractive from a cost perspective. Nonetheless, despite the necessity for a more complex design, XGI plans to undercut the prices of NVIDIA’s and ATi’s competing high-end products with its Volari Duo line.
XGI will be offering two dual-chip cards :
- Volari Duo V8 Ultra : twoV8 Ultra chips with 8 pixel pipelines each, core frequency per chip : 350 MHz, memory frequency : 375 MHz with DDR, 500 MHz with DDR2
- Volari Duo V5 Ultra : two V5Ultra chips with 4 pixel pipelines each, core frequency per chip : 350 MHz, memory frequency : 375 MHz with DDR, 500 MHz with DDR2
Board Partners
Following NVIDIA’s strategy, XGI plans not to build, market and sell its own cards, instead concentrating only on the design and production of the chips themselves. XGI leaves the production and sale of the cards as retail products to its partner companies. C.P. Technology, better known under its label PowerColor, and Club-3D are already confirmed to be among XGI’s partners. It is rumored that other companies such as ASUS, ABIT, Gigabyte, and MSI may soon follow. When asked, MSI and ASUS responded that they were not planning to produce any XGI-based cards in the foreseeable future. Gigabyte, on the other hand, confirmed that there were definite plans for cards based on XGI chips. Another likely candidate could be ECS Elitegroup. This company has strong ties with SIS, already having offered a full selection of SIS Xabre based cards in the past.
First Contact With The XGI Volari Duo V8
After all this theory, we can finally get to the practical part of the review. XGI was kind enough to send us a sample of the XGI Volari Duo V8 Ultra, which we would like to present to you on the next few pages. Please note, however, that the card is a prototype, and as such, both the card and the drivers are still under development. For example, the DDR-2 memory of our card only ran at 450 MHz instead of the 500 MHz specified for the final card. Also, we ran into some overheating problems during testing. But let’s begin with a look at the card.
The card offers the usual complement of connectors : 1xSubD, 1xTV-out and 1xDVI. Using an adapter, the DVI will also work with a regular SubD cable.
Two fans cool the card. The memory modules also receive cooling. During operation, this card is quite loud, but, according to XGI, this is the not yet final design.
The back of the card is cooled by a passive heatsink. Due to its height, some users may run into problems installing it, since some motherboard components may get in the way.
