Board analysis

Top of the GeForce 7950 GX2 card

Bottom of the card

At an angle, you can see the 2nd PCB

At first glance, the GeForce 7950 GX2 looks like one card with one GPU and one heatsink/fan unit at some angles, particularly when looking at the card from directly above. Tilt the board a few degrees though and you’ll quickly see a second PCB lying underneath the first PCB, complete with its own GPU and heatsink/fan unit, 512MB of memory, as well as the underlying x16 PCI Express graphics interface.

Each heatsink/fan unit is rather slim, a little larger than the reference cooler used on the GeForce 7900 GT basically, being a single-slot design. The two PCBs are then grafted together, so one GeForce 7950 GX2 will take up two slots in your system. The PCI Express graphics slot sitting directly above the card, as well as the slot directly adjacent to your graphics card. This is the same setup NVIDIA used previously on their GeForce 7900 GX2 Quad SLI card.

GeForce 79XX Specifications
	GeForce 7950 GX2	GeForce 7900 GTX	GeForce 7900 GT
Core Clock Speed (Vertex, core)	500/500	700/650	470/450
Memory Speed	600MHz	800MHz	660MHz
Pixel Shaders	24x2=48	24	24
Vertex Shaders	8x2=16	8	8
ROPs	16x2=32	16	16
Memory Interface	256-bit per GPU	256-bit	256-bit
Memory Onboard	512MB per GPU 1GB total	512MB	256MB
Pixel Fill-Rate	16	10.4	7.2
Texture Fill-Rate	24	15.6	10.8

While the GeForce 7950 GX2 sports a new name, technically the new card is quite similar to its predecessor: no changes are made to the GPU itself. NVIDIA outfits the GeForce 7950 GX2 with two GPUs derived on their 90-nm G71 graphics core. Housed inside the GPU are 24 pixel shaders and 8 vertex shading units, just like the GeForce 7900 GT or GTX, the GeForce 7900 GX2 and 7950 GX2 also run at the same clock speeds: 500MHz on the graphics core and 600MHz for the memory. This is considerably slower than the speeds of 650MHz core/800MHz memory found in the GeForce 7900 GTX, actually placing the GeForce 7950 GX2 closer to the GeForce 7900 GT’s speeds of 470MHz core/660MHz memory. This means that a single GeForce 7950 GX2 card won’t match the performance of a pair of 7900 GTX cards running in SLI, but should definitely be faster than a single GeForce 7900 GTX.

Since the 7950 GX2 and 7900 GX2 share similar clock speeds, performance between the two boards is the same in a single-card configuration.

Instead of performance, the key difference between the GeForce 7950 GX2 and the GeForce 7900 GX2 lies in the board’s design; weighing in at just 9” long, the GeForce 7950 GX2 is considerably shorter than the GeForce 7900 GX2 board it replaces. This makes the card easier to fit in most cases, not to mention more breathing room for installing other devices such as hard drives. The original GeForce 7900 GX2 board was so long that it could get in the way of these devices.

Note the size difference between the 7900 GX2 and 7950 GX2

Only one 6-pin power connector on the 7950 GX2

SLI bridge connection on 7950 GX2

But the changes don’t stop there, as NVIDIA has also removed one of the SLI bridge connectors on the GeForce 7950 GX2, as well as one of the 6-pin PCI Express power connectors on the board. Previously the GeForce 7900 GX2 required two 6-pin power connections to run properly, meaning you needed four different power cables to run Quad SLI! This extra cabling takes up even more space in your case, and of course requires you to run additional power cables to your graphics cards.