NVIDIA Quad-SLI vs. ATI Crossfire 34

NVIDIA Quad-SLI vs. ATI Crossfire Review

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A closer look

What is important with the PCB design is that the two card parts are interconnected by an own PCI-Express bus and an own SLI connector. Both are just sized down versions of the regular connectors.


The little PCB on the left is a fully functional PCI-Express connector and to the right of it sits a PCB for the SLI bridge interface.


One little problem is that these two connectors block the outgoing airflow of one cooling fan. The reason why the connector is where it is now, is the PCB routing, all individual signals of the PCI-E bus have to have the same trace length, otherwise the bus becomes unstable.


This PCI-E to PCI-E bridge chip is interfacing with the motherboard's PCI-Express bus on one side and on the other side it implements its own bus for the two cards (the two cards which are part of one GX2 card) to exchange data.


The memory is arranged on one side, closely around the GPU like we know it from all modern NVIDIA and ATI video cards.


As memory chips Samsung K4J52324QC-BC14 is used. With a nominal speed of 1.4 ns it should run at least 700 MHz real clock.


These are the power connectors. Each "card" needs its own supply of power which means you will need four power connectors for a Quad-SLI system. If your PSU doesn't have four connectors, which it most probably doesn't you can use a 5.25" to PCI-E power conversion cable.


This is the heart of Quad-SLI, a G71-D-N GPU. The same as on the 7900 GT(X), the A2 stands for the revision.
As mentioned before, to make sure the cards don't overheat, NVIDIA chose to reduce the core clock by 150 MHz down to 500 MHz.


As output only DVI is available. If you spend so much money on video cards you better have a high-res LCD panel with DVI input. Of course wide-screen gaming is fully supported by the 7900 GX2 and after playing on the huge 30" Apple LCD I can only recommend it to everybody. Not only does it look great, it also gives you a bigger viewing angle, possibly showing an enemy which wouldn't have been visible on normal apect ratio - going wide-screen will give you more frags.
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