With the power needed by the GeForce 9800 GX2, it is critical that a system be equipped with a proper power supply. To power the GeForce 9800 GX2, a 6-pin and an 8-pin PCI-Express connector are required. In this case, it is best left to refer to the list of SLI-certified power supplies at NVIDIA's SLI Zone for recommendations.
Those who may be considering a GeForce 9800 GX2 will likely need to replace their systems' power supply. Unfortunately, expensive power supplies used to power the GeForce 8800 GTX 8800 Ultra in SLI will not be usable on the GeForce 9800 GX2 due to the lack of an 8-pin PCI-Express connector.
Tagan TG1100-U96 Turbojet Power Supply
The Tagan TG1100-U96 Turbojet Power Supply was used during this review, which performed as expected, but used a plastic retention clip on the 8-pin PCI-Express connector that was too wide to fit in the slot on the graphics card. Forcing the connector is not recommended since the slot could become damaged as pictured below.
In the event that this problem should occur, a file can be used to make the slot a bit wider. This was much easier to file than the plastic retention clip on the power supply.
Wider Slot Workaround
NVIDIA is aware of this problem and passed along a couple of things that are being done to help alleviate this issue:
Some PCI-E connectors may have trouble fitting into the 8-pin socket on the GeForce 9800 GX2. We designed our socket to specification, but unfortunately some power supply manufacturers did not. With a bit more force, most of these plugs will fit. Two things are being done to alleviate this issue. First, board vendors will be making available adaptors to help the oversized plugs work with the GeForce 9800 GX2. Second, PSU manufacturers are updating their designs to follow PCI-E specification. Please contact your board vendor or PSU vendor for further details.
Pictured below is an important word of caution that explains the distinction between the 8-pin motherboard power connector versus the 8-pin PCI-Express connector. Each connector has different shaped connectors and a warning is provided to help ensure that the motherboard connector is not accidentally inserted into the graphics card.