Nvidia announces the GTX 690 – Dual GPUs
The industrial design of the GeForce GTX 690 is a direct reflection of what lies beneath the cover: two Kepler GPUs, tremendous graphics horsepower, and a product of exceptional longevity. Visually, the design draws parallels to an F1 engine block with its raw metal look and exposed fin stacks.
The card’s front plate is composed of two different materials. The exterior frame is made of cast aluminum with trivalent chromium plating, giving the board a durable, matte finish. The central fan housing is created from injection molded magnesium alloy.
Magnesium alloys are used throughout the automotive and aerospace industry (including the engines of the Bugatti Veyron and F-22 Raptor) for their light weight, heat dissipation, and acoustic dampening properties. To create the intricate geometries required for the fan housing, we used a form of injection molding called thixomolding, in which liquid magnesium alloy is injected into a mold. This allows us to create fine geometries and a tight, perfectly coupled fit.
The GeForce GTX 690 is cooled via a pair of custom vapor chamber heat sinks. Unlike a traditional heat sink that uses conduction to move heat away from the GPU, a vapor chamber exploits the superior heat conducting characteristics of evaporation. Inside each vapor chamber is a small amount of purified water. As the GPU heats up, the water evaporates, carrying away heat in the process. Once the vapor reaches the top of the fin stack, it cools, condenses, and the process repeats itself. It’s similar to a miniature form of water cooling but, because the liquid is entirely self contained, there’s no need for tubing and no chance of leaks.
Channeling air through the heat sinks is a center-mounted axial fan. The smoother the airflow, the lower the noise output. Here, our engineers spent considerable effort optimizing the fin pitch and angle at which the air hits the fin stack. The area directly underneath the fan is carved with low-profile channels to encourage smooth airflow and all components under the fan are low-profile so they won’t cause turbulence or obstruct airflow. Our acoustic engineers also fine-tuned the fan’s control software so changes in fan speed occur gradually rather than in discrete steps.
A dual-GPU graphics card is similar to two-way SLI condensed into a single graphics card. Historically, though, the dual-GPU card has always lagged behind its SLI counterpart in terms of performance. When two GPUs are brought onto the same card, their combined heat output outstrips the capacity of even the most capable cooler. As a result, clock speeds must be lowered. For example, in the Fermi generation, the fastest single-GPU graphics card had a graphics clock speed of 722 MHz and a memory data rate of 4008MHz. On the dual-GPU card, the graphics clock was 607 MHz and the memory data rate was 3212 MHz.
This is where Kepler’s fanatical focus on power efficiency pays off most handsomely. The GPUs on the GeForce GTX 690 have a boost clock of 1019 MHz, just a hair (2.8%) shy of the GeForce GTX 680 at 1058 MHz. What’s more, all other specs are identical; the number of cores, memory speed, and memory bandwidth per GPU are the same on both cards.
|Base Clock||915 MHz|
|Boost Clock||1019 MHz|
|Memory Configuration||4GB / 512-bit GDDR5|
|Memory Speed||6.0 Gbps|
|Power Connectors||8-pin + 8-pin|
|Bus Interface||PCI Express 3.0|