The GF 7800 GTX 512MB & Asus A8N32-SLI
We've put together a simple chart comparing some relevant performance characteristics to give you an idea as to how the GeForce 7800 GTX 512MB stacks up against the rest of today's high-end graphics cards. Please note that the clock speeds listed below represent NVIDIA's and ATI's reference specifications. Many retail partners ship their products at higher clock speeds than are listed below...
When compared to the 256MB GeForce 7800 GTX the new 512MB GTX has significant advantages in every category, due to its higher core and memory clock speeds. As per NVIDIA's reference specifications, the GeForce 7800 GTX 512MB has a core GPU clock speed of 550, up from 430MHz on the 256MB GTX, with a 1.7GHz (DDR) memory speed, up from 1.2GHz. These clock speed increases give the GeForce 7800 GTX 512MB a 2GPixel/s and a 2.9GTexel/s advantage in peak fillrate, and an additional 16GB/s of available memory bandwidth. The GeForce 7800 GTX 512MB can also process more vertices per second thanks to its higher core clock speed, 1.1 billion vs. 860 million. When compared to ATI's current flagship, the Radeon X1800 XT, the GeForce 7800 GTX 512MB has advantages in every category except for pixel fillrate, where the X1800 XT's 625MHz core clock speed gives it a 1.2GPixel/s edge.
If you're familiar with NVIDIA's Quadro line of workstation graphics cards, the GeForce 7800 GTX 512MB may look somewhat familiar. The new 512MB GTX is equipped with a two-slot cooler, similar to the one used on the Quadro FX 4500. The cooler has a large copper heat-plate in the center and is flanked by two large banks of aluminum fins. Connecting the heatsink's fins to the heat-plate are four liquid filled heat-pipes (two per side). In the center of the cooler is large, variable speed fan that blows air over the heatsink's fins, where its then exhausted from the system through vents in its mounting plate.
There are a few other things that differentiate the GeForce 7800 GTX 512MB from its 256MB cousin as well. As we noted in the chart above, the 512MB 7800 GTX's GPU is clocked at 550MHz; its 512MB of GDDR3 RAM is clocked at an impressive 1.7GHz (850MHz DDR). The configuration of the GeForce 7800 GTX 512MB's RAM also differs from the 256MB GTX in ways other than clock speed. 256MB GeForce 7800 cards have 128MB of RAM situated on either side of the card, whereas the new 512MB GTX uses higher-capacity chips that are all mounted to the front side of the PCB. The configuration of the 512MB card's VRM is similar to a GeForce 7800 GTX 256MB, however, as they both have a relatively large aluminum heat sink mounted to their MOSFET power arrays.
GeForce 7800 GTX 512MB cards sport dual-DVI outputs and a TV output, along with the same SLI connector found on other SLI enabled GeForce cards. The DVI and TV outputs can be used to power dual independent displays simultaneously, or four displays should two 7800 GTX cards be installed in a system.
Another piece of NVIDIA powered hardware we'd like to give some attention to, is the motherboard we used for testing throughout this article. We upgraded our test system with an Asus A8N32-SLI motherboard, which is based on the relatively new nForce 4 SLI X16 chipset. The nForce 4 SLI X16 has essentially the same feature set as the original nForce 4 SLI chipset, but with more PCI Express lanes. The nForce 4 SLI X16 chipset offers two full-bandwidth PEG slots, each with 16 PCI Express lanes of their own. The original nForce 4 SLI offers only 8 PCI Express lanes to each PEG slot when configured for dual-graphics cards. The addition of the Asus A8N32-SLI, along with new chipset and graphics drivers gave our NVIDIA based test system a measurable performance boost, as you'll see on the page ahead.