Like the GeForce 7950 GX2 before it, the 9800 GX2 utilizes a dual GPU, dual PCB board design. This increases the manufacturing cost of the board, as dual PCBs are required, but with dual PCBs NVIDIA has more freedom when routing traces from the GPU to memory. NVIDIA also mentions that their dual PCB design allows heat from the GPU and its power circuitry to be dissipated by its own dedicated PCB, rather than spreading heat from two GPUs across one PCB.
See the vents on the back edge of the card, directly underneath the power connectors? These vents are for the card’s fan. Air from within the case is drawn in from both sides of the graphics card through these vents. This air is then pushed by the fan over the GPUs, where they are both cooled. The air then exhausts out the side of the graphics card as well as outside the system case. Like previous high-end GeForce GPUs, the fan used by NVIDIA on the GeForce 9800 GX2 is a variable speed fan and it runs quietly. NVIDIA continues to completely enclose their high-end cards to reduce the chance of accidental damage during shipping (say for instance, a capacitor breaks off) as well as protect the card from electrostatic discharge.
Powering the GeForce 9800 GX2
The GeForce 9800 GX2 ships with two power connectors, a 6-pin PCIe connector and an 8-pin PCIe 2.0 connector. Both the 8-pin and the 6-pin connector are required in order for the card to operate. One interesting snag that we literally ran into with the GeForce 9800 GX2 was related to the 8-pin connector.
With NVIDIA using a metal enclosure surrounding the 9800 GX2 card and its power connectors, power sockets had to be cut into the top of the enclosure for PCIe power connectors. Unfortunately, the socket for the 8-pin connector is too small to fit with the 8-pin PCIe connectors used by many power supply manufacturers: the plastic tab on the top of the PCIe 2.0 connector is literally too large to fit inside NVIDIA’s power socket, and as a result, you literally have to jam the PCIe 2.0 power cable into the socket in order for the connector to get plugged in. You can see an illustration of what we’re talking about in the following images:
We’ve been told by NVIDIA that their socket conforms to PCIe specifications and it’s the power supply manufacturers who have been producing PCIe 2.0 power cables that don’t comply with the spec. The bottom line is that the power cables on some power supplies fit better than others, so you will want to check NVIDIA’s list of 9800 GX2-certified power supplies on slizone.com
beforehand to avoid running into this issue.
Bling on the 9800 GX2
The GeForce 9800 GX2 card is filled with LEDs. There’s a bank of LEDs surrounding each power connector, and more LEDs on the card’s backplate, as well as the exhaust area beside the primary DVI connector. The LEDs located next to the power connector are used to alert the end user if the card’s power is connected incorrectly: green LEDs indicate that the connector is properly connected, but if the LEDs shine red you know you hooked the card up wrong. Say for instance you hook the card up to your power supply solely using dual 6-pin PCIe connectors. Since the GeForce 9800 GTX requires an 8-pin connector and a six-pin connector, the LEDs surrounding the 6-pin connector would light up green, while the LEDs around the 8-pin connector would glow red.
Obviously if you’ve got the GeForce 9800 GX2 card housed inside your system chassis and your case is closed (and it doesn’t have a window on the side allowing you to peek inside), you won’t be able to see if the LEDs are glowing red or green. In this case, NVIDIA provides an additional power LED on the backplate of the card. Located above this LED is a blue LED which is used for indicating the primary display. This LED is useful for Quad SLI setups where the primary graphics card driving your monitor may be difficult to identify.
On the backplate of the GeForce 9800 GX2 card itself you’ll notice two DVI connectors, as well as an HDMI connector. The HDMI connector and the DVI connector next to it are bootable, while the secondary DVI connector can be used to drive an additional display. For sending audio over HDMI, NVIDIA also provides a SPDIF connector on the GeForce 9800 GX2 located next to the PCIe power connectors. This connector must then be hooked up to the SPDIF header located on your motherboard or sound card.