Motherboards based on the 780i chipset have very slowly started showing up on hardware review sites in the last few weeks, but what are they offering? And why do you want one? Read on to find out.

The new “Enthusiast” level platform, which is nVidia’s highest level for the desktop PC, is all focused around the new nForce 780x chipset. Unlike the previous nForce 680i chipset, which was only for Intel processors and left AMD lovers with nForce 430, 630, 520 and 570 chipsets just to make everything nice and confusing for everyone, the 780x chipset is made for both platforms, 780i for Intel, and 780a for AMD. A “Performance” level platform is also becoming available with the nForce 750x chipset, but we’ll get to that later.

3-Way SLI Support:

The main benefit of the 780x chipset is true 3-Way SLI support, which is currently supported by the GeForce 8800 GTX and Ultra range of cards only, so it really is reserved for the pointy end of the market. Along with 3-Way SLI support, the motherboards (in conjunction with the video cards) have support for the craziest resolution anagram I’ve ever seen – WQUXGA – which translates to a resolution of 3840x2400, or over twice the resolution on each axis (so 4 times the pixels) of a true 1080i/p HD image, which is only 1920x1080. I can’t wait to see the screen that comes with WQUXGA support, THAT will be impressive.

ASUS P5N-T - One of the first nForce 780i Chipset Motherboards

Unlike old SLI systems which often split the PCI-Express ports down the same x16 path to make each PCI-Express connector run at x8 speed, all three PCI-Express x16 slots on the 780i chipset run at full x16 speed, with two slots being PCI-Express 2.0, and the third being PCI-Express 1.0 only.

The full details of the PCI-Express graphics slots for each chipset are as follows:

• nForce 780i – 2 x PCI-Express x16 (2.0), 1 x PCI-Express x16 (1.0)
• nForce 780a – 1 x PCI-Express x16 (2.0), 2 x PCI-Express x8 (2.0) (all x16 length slots)
• nForce 750i – 1 x PCI-Express x16 (2.0), 1 x PCI-Express x8 (2.0) (both x16 length slots)
• nForce 750a – 2 x PCI-Express x8 (2.0) for SLI, 1 x PCI-Express x8 (?) non-SLI capable (all x16 length slots)

So as you can see, the only chipsets to offer support for 3 x PCI-Express x16 slots is the Intel version of the 780 chipset, the AMD version has to settle for having two of its slots running at just x8 speed, which is sure to hurt the performance. And let’s face it, if you’ve paid for a 780 chipset motherboard and 3 (!) 8800GTX’s or Ultra’s, you’d expect the absolute best performance possible, but if you chose to run that with an AMD CPU, then that’s never going to be the case, simply due to the chipset’s limitations – quite disappointing.

The nForce 750 chipsets have no support for 3-Way SLI, and no matter which CPU platform you chose, it will not be able to run both SLI cards at full x16 speed, and only the Intel version can run even one of the cards at full x16 speed, the AMD version has them both running at x8 speed when using SLI, a bit of a disappointment for a new-generation board/chipset.

3-Way SLI differs to its previous 2-Way configuration in the way it renders the video stream. In a normal 2-Way SLI system, half the frame is rendered by one card, while the other half is rendered by the second, however with a 3-Way SLI system they use Alternate Frame Rendering as standard, which means card #1 renders frame #1, card #2 does frame #2 and card #3 does frame #3. This should mean less strain on the CPU, but what actual difference it’s going to make if any is really yet to be seen.

Another problem with 3-Way SLI, and indeed all SLI system is the diminishing return you get with the more you spend. With a 2-way SLI system, you spend 100% more on a second video card and get (at very best) an 80% performance increase, often much less. With a 3-Way SLI system, the return on your investment is even worse, the second card will give you (at best) an 80% increase over the first card, and while in theory the third card should give you another 50% increase over what the first two are already delivering, you’d be lucky to get 25-30% in the best case scenario. So would it ever really be worth it going to 3-Way SLI? I’m already dubious about the value of 2-Way SLI, so my opinion on this will be pretty clear.

To run 3-Way SLI on a 780x chipset, you will need Windows Vista and you will need an 1100W PSU minimum! This is turning into one hell of an expensive machine to build, considering it will be outdated in 6 months no matter how much money you spend on it.

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