DFI LanParty nF4 SLI-DR Review - PAGE 12

SLI Testing

With SLI, we felt a need to go a bit beyond the usual motherboard benchmarks and take a look at how a board performs in a SLI configuration and also to get a taste of what to expect while overclocking. DFI has chosen to implement a jumper system to toggle between SLI and single card mode. The jumper system also allows for more lanes to be routed to the PCIe x4 slot from the default of x1 bandwidth to x4. The jumper process is more time consuming than card method seen on most of the other boards but I think there is arguably less ambiguity with this method. Upon the arrival of our first Gigabyte SLI board, we had a small debate as to whether it was in SLI or Normal mode.

There are a couple of quirks with with SLI mode enabled - unless two video cards are plugged in while it is in the SLI configuration, the board will not POST with a single video card plugged into either slot. This was not the case when testing the Gigabyte boards. DFI says that this is planned functionality. A second quirk was the way that the video cards were initialized before SLI was enabled through the NVIDIA drivers - on the first video card, there would be output during the boot process, but once the video card drivers were initiliazed by Windows, the display would go blank. On the second card, there would be no output during the boot up sequence but then after the drivers were initialized by Windows, the display would appear. After enabling SLI through the driver control panel, the video output on the first card worked correctly for both the boot process and Windows.

In the charts below are four different configurations -

DFI LanParty nF4 SLI - this is the default configuration used in the motherboard benchmarks. Games are run witih low quality settings where indicated. Clock rate on the processor is 200x9 which gives 1800 Mhz

Single 6600GT @ 640 - this is an OVERCLOCKED configuration. Game settings are the same ones used as the default motherboard configuration setup. Clock rate on the processor is 250x9 giving 2250 Mhz. Memory timings remain unchanged and are at a 1:1 ratio. This is strictly a 25% increase in clockrate.

Single 6600GT @ 1600 - this is an OVERCLOCKED configuration. Clock rate on the processor is 250x9 giving 2250 Mhz. Memory timings remain unchanged and are at a 1:1 ratio. Graphics settings ARE changed. Resolution is changed to 1600x1200 with the game settings maxed out. AA/AF is not applied, but details, texture quality and everything else is maxed out. This will be a typical graphical configuration when playing games.

SLI 6600GT @ 1600 - this is an OVERCLOCKED configuration. Clock rate on the processor is 250x9 giving 2250 Mhz. Memory timings remain unchanged and are at a 1:1 ratio. Graphics settings ARE changed. Resolution is changed to 1600x1200 with the game settings maxed out. AA/AF is not applied, but details, texture quality and everything else is maxed out. This will be a typical graphical configuration when playing games. We throw in the second 6600GT card and enabled SLI to see the performance benefits that should be expected from a handful of games.

A 25% in clockrate gives a 24% boost in framerates. DOOM 3 at 640 is very processor dependent. When the resolution is raised and the graphic options that make DOOM 3 so pretty is turned out, the framerate drops to 46.2 FPS. Dropping the second 6600GT card in there raises the framerate 66%, up to 76.6 FPS

Again at 640x480 we get nearly a 25% bump in the framerate - the clockspeed and framerate are linked linearly. Raising the resolution to 1600 drops us to 41.476.40 FPS. Adding the second 6600GT results in a 85% boost in framerates at 1600.

Once again the framerate increase from the processor overclock is roughly 24%. Raising the bar up to 1600x1200 and maxing out the graphical features does not hurt the framerate nearly as much as DOOM3 or Halo. In SLI mode, the increase in framerate is merely 15%.

With X2, we have do not have the strict CPU bound that was seen with the previous three games. This time, the overclock results in only a 13% jump in framerates. Turning on shadows and raising the resolution to 1600 put a big strain on the 6600GT. With SLI enabled there is a 36% increase in framerates.