|Gigabyte GV-NX98X1GHI-B GeForce 9800 GX2 Video Card|
|Reviews - Featured Reviews: Video Cards|
|Written by Olin Coles|
|Tuesday, 25 March 2008|
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GV-NX98X1GHI-B Detailed Features
In our last section, we skimmed over the outer skin of the new GeForce 9800 GX2. With a basic understanding of what you'll get on the outside, we're ready to get inside the product and dissect the technology. This information will be very helpful for those hardware enthusiasts and overclockers willing to void there warranty and potentially ruin their expensive product in order to tweak it's electronics. This information is for informational purposes only, and not a recommendation to disassemble your product.
Before we go and take apart our brand new 9800 GX2, let's revisit some of the finer functional points introduced with this product such as the HDMI audio output and power handling. Because the HDMI audio functionality is controlled at a hardware level, there is no need for additional drivers or software. Much like the SPDIF connection on the back of a motherboard, the video cards audio out function is plug-n-play. The P/SPDIF cable included with the kit connects between the small two-pin port on the 9800 GX2 and the HT Omega Claro Plus+ AD8620BR Op Amp sound card we used for testing. Your setup may be different, so the cable connects between the GX2 and either your motherboard or sound card digital input pins. Not all motherboards and sound cards support this option, so make sure it's available before you make your purchase. The 9800 GX2, unlike other NVIDIA cards, is equipped with the PureVideo 2 engine for GPU assisted decoding of the H.264 and VC-1 CODEC's. This in an important NVIDIA factoid that plays well into our own benchmarks later on in this article.
In regard to the new power requirements, the GeForce 9800 GX2 has two hungry mouths to feed so you can expect the consumption to be on a higher order. An eight-pin and six-pin PCI-Express power connections are both required to run the 9800 GX2. NIVIDA has designed the G92 graphics processor to be an efficient cornerstone to the 9th Generation of GeForce products.
Compared to the 8800 GTX, it should please you to learn that the Gigabyte GV-NX98X1GHI-B graphics card consumes almost the same amount of power under high-power full 3D load. In comparison to our (extremely) overclocked G80-based GeForce 8800 GTS 640MB which consumes 72 additional watts of power when switching from low to high-power mode, the Gigabyte 9800 GX2 increases power demand by 83 watts. Alternatively, the the G92-based ZOTAC GeForce 8800 GT AMP! Edition only raises the level 59W under full load.
EDITORS NOTE: Some add-in card partners have included power-connection adapters with GX2-series video card. Benchmark Reviews advises users NOT to use any connection adapters, as it may create a dangerous load on the power supply unit or electrical wall source.
As I prepared to disassemble the shiny 9800 GX2, there were a few subtle clues that gave away the inner workings of the Gigabyte GV-NX98X1GHI-B before I ever opened up the enclosure. Aside from the trimmed-off PCI-Express card slot on the opposite side of the GX2, there was the tell-tell sign of two NVIDIA GeForce 9800 GX2 products needing drivers loaded and then displayed in the Windows Device Manager.
I have read a lot of speculation claiming that the GeForce 9800 GX2 is a dual-GPU graphics card, and I believe that depending on the definition there might be some argument over the semantics. There are two GPU's inside the 9800 GX2 enclosure, so that much is true, but they are on two separate printed circuit boards which face towards each other and are then linked by a PCI (Express) bridge. This assembly creates two tightly-combined independent graphic cards into one singular video card package. It is however very different from the Radeon HD 3870 X2, which places two GPU's directly onto the same PCB. So essentially the GX2 is no more a dual-GPU unit than an Intel LGA775 socket consisting of a dual-core CPU. Again, it's semantics and how you define the technology.
The up-side to this design is that each GPU dissipates heat onto its dedicated PCB. On a single-board design, both GPUs dissipate heat onto the same PCB, in effect transmitting heat to each other.
With two separate PCB's facing in towards each other, NVIDIA has designed a single blower fan using SmartFan technology to actively cool the two GPU's inside the 9800 GX2. While air is pulled in from the all five sides at the end of the graphics card, it is exhausted at each side of the unit and through a small opening of approximately one inch at the header end of the video card. Obviously it would be most ideal to have all heated air exhausted outside of the computer case, but because of the populated I/O header panel design a single dedicated exhaust air channel is not possible.
By design, the two printed circuit boards are pressed onto each side of the cast-aluminum heatsink sandwiched into the middle. Additional thermal conductive pads are strategically placed between key components such as DDR3 vRAM modules and the heatsink. Gigabyte also uses a pre-applied carbon-based Thermal Interface Material (TIM) between the GPU and the copper base inset into the heatsink. Even though NVIDIA ditched the heatpipes last seen in their 8800 GTS/GTX/Ultra reference design, it seems that there might be room for them if an add-in card partner wanted to improve upon the design.
A 256-bit memory bus allows the Gigabyte GV-NX98X1GHI-B GeForce 9800 GX2 to offer 512 MB for each GPU, for a total realized video frame buffer of 1024 MB (1 GB). Gigabyte does not overclock this portion of the product in the GV-NX98X1GHI-B, primarily because of the delicate synchronization of the two PCB halves through the PCI bridge. Benchmark Reviews discovered another good reason, which we share later in our overclocking results section. If money's no object to you however, the 9800 GX2 could be great news for gamers and hardware enthusiasts wanting to connect two of these cards into a "quad" SLI array on one of the new nForce 790i motherboards.
This concludes our look at the Gigabyte GV-NX98X1GHI-B, and from here on out the 9800 GX2 must either put up results or be put down. In our next section, Benchmark Reviews begins testing on the Gigabyte GV-NX98X1GHI-B GeForce 9800 GX2 video card after we spend some time explain how it's all done here in our lab.