X-bit labs

Two for One: Nvidia's Dual-Chip GeForce 7950 GX2 Reviewed (page 4)

Category: Video

by Alexey Stepin , Anton Shilov

[ 06/09/2006 | 06:01 PM ]

PCB Design

Similar to the GeForce 7900 GTX2, the GeForce 7950 GX2 graphics card is a two-storied device that consists of two PCBs placed one above another.

However, this card is more compact because it is shorter. It is comparable in size with Radeon X1900 XTX or GeForce 7900 GTX. Although the GeForce 7950 GX2 is still somewhat longer than the modern single-chip flagship solutions from ATI and Nvidia, it should fit perfectly into any standard system case of ATX form-factor. It may be troublesome to install this card into a small system case, but top-performance gaming stations this product is targeted at don’t generally come in small sizes.

The PCBs are connected into a single whole by means of four metal hexahedral posts. We unfastened the four screws and took the GeForce 7950 GX2 apart. We also dismantled both coolers for you to have a better view of the design of the new device from Nvidia:

As you see, the bottom PCB bears much more components than the top one because it is equipped with a PCI Express x16 slot and carries a PCI Express x48 switching chip besides one of the two G71 processors.

You can read the marking of both the chips in the snapshot. The GPU is an ordinary sample of G71 D-H-N revision A2 dated the 14th week of 2006. The bridge chip is marked as BR03, has A3 revision, and is dated the 13th week of the same year. According to Nvidia, the switch chip is only responsible for allocation of the PCI Express lanes between the two GPUs whereas synchronization of the GPUs is performed via MIO interface as in traditional Nvidia SLI configurations.

Also on this PCB there is a power circuit (not a very complex one due to the low power consumption of the G71 chip), a connector for the top card, and a MIO connector. The latter connects two GeForce 7950 GX2 cards to work as a quad-SLI subsystem, but it is unclear how this connector is used if the MIO interfaces of both the GPUs in a GeForce 7950 GX2 are already connected internally.