SLI Performance and details

NVIDIA will have an SLI-certification program for motherboard manufacturers and video card manufacturers. All products with the SLI-certified seal have been tested and approved to work by NVIDIA.

Setting up an SLI system

Officially, you’re supposed to combine two SLI graphics cards of the same type and the same manufacturer for SLI to work, but we’ve been told that you can cross combine manufacturers with no problems. This means that you should be able to combine, for instance, an eVGA GeForce 6800 Ultra with an ASUS GeForce 6800 Ultra. You can also cross combine board revisions and card BIOS revisions with no problems. However, you can’t combine a GeForce 6800 GT with a GeForce 6600 GT for SLI, or a 128MB GeForce 6600 GT with a 256MB card.

Power requirements are normal for GeForce 6600 GT SLI, but NVIDIA recommends a 550-watt power supply for GeForce 6800 Ultra SLI. We were also told that motherboard manufacturers will be providing the SLI connector in the nForce4 SLI packaging, so when you buy that shiny new nForce4 SLI motherboard, make sure to check that it comes with an SLI connector, obviously nForce4 Ultra motherboards won’t ship with SLI connectors. The first manufacturers with nForce4 SLI motherboards will be ASUS, Gigabyte, and MSI, with others to follow.

Ever since SLI was first announced, gamers have been dying to know how well it performs. Unfortunately, we don’t have an nForce4 SLI motherboard to test with just yet, but we were given the following numbers by NVIDIA:

SLI Performance
	GeForce 6600 GT
	Single	SLI	% Increase
DOOM 3	17.3	32	85
Halo	37.23	58.58	57
3DMark 05	3186	5698	85

SLI Performance
	GeForce 6800 GT
	Single	SLI	% Increase
DOOM 3	37.9	65.2	72
Halo	50.01	72.76	45
3DMark 05	4588	8271	80

SLI Performance
	GeForce 6800 Ultra
	Single	SLI	% Increase
DOOM 3	42.4	71.7	69
Halo	57.21	79.01	38
3DMark 05	5211	9297	78

Test system specs are an ASUS prototype nForce4 SLI board with an Athlon 64 4000+ CPU. All numbers in Halo and DOOM 3 taken at 1600x1200, while 3DMark 05 was run at 1024x768.


Speaking of performance, one feature that nForce4 continues to provide that was first found in nForce3 250Gb is GeForce-specific optimizations in hardware. In short, NVIDIA has added special pathways to nForce4 that allow it to run faster once a GeForce 6 series graphics cards is installed in the system. This applies to both SLI and non-SLI configurations, as well as all nForce4 variants, including the vanilla nForce4 chipset. NVIDIA made it clear that nForce4 does not detune the performance of their competitors’ product once it’s installed in nForce4. In other words, think of it as SURROUNDVIEW, but for performance instead of multi-monitor support.