The EVGA and XFX GeForce 7900 GTX graphics cards were tested on two nForce4 SLI motherboards. Note the clearance between the two graphics card on the Gigabyte GA-8N-SLI Pro motherboard, which is about 1/4 of an inch.
Clearance on the Gigabyte GA-8N-SLI Pro
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In a single card configuration with minimal system load, the GPU temperature of both graphics card ranged from 38° C to 42° C. In SLI mode, the GPU temperature of the top graphics card was 10° C higher than the GPU temperature of the bottom graphics card.
GPU Temperatures on the GA-8N-SLI Pro
On the Asus A8N-SLI Premium motherboard, the clearance between the two graphics cards is about an inch. The additional space allows more air to circulate around the graphics cards, which aids in cooling.
Clearance on the Asus A8N-SLI Premium
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The extra space on the Asus A8N-SLI Premium motherboard paid off as the temperature variance between the top and bottom GPUs was only 5° C. The following readings are from the nV Monitor utility, which is part of NVIDIA's nTune optimization and monitoring application. For a list of nForce3 and nForce4 motherboards that are compatible with nTune, click here.
GPU Temperatures on the A8N-SLI Premium
In either case, the heat that can be generated from a high-end SLI system is impressive. The air temperature being exhausted from the top of the case with the Asus motherboard exceeded 100° F after looping through Far Cry's Regulator timedemo for 30 minutes.
Temperature of Exhausted Air
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Prior to the benchmarking session, the room temperature was 70.9° F. Some 30 minutes later, the temperature rose to 77.2° F. On hot summer days, heat becomes an issue - even with central air conditioning. A water-cooled system will keep temperatures down as will the awesome all-in-one Thermaltake Tide Water GPU Cooler.
Another solution would be to install a small window unit air conditioner. Use headphones when gaming to drown out noise from the air conditioner should it become a problem.
