nForce 4 SLI X16: Full Speed PCI Express
by Derek Wilson on August 8, 2005 1:56 PM EST- Posted in
- CPUs
Introduction
Ever since its launch in the fall of last year, nForce 4 has brought us SLI capability. Configurations for PCI Express slots in nForce 4 SLI motherboards must be selected by using a paddle that can be flipped to allow for either 2 x8 connections or full bandwidth for one with the other disabled. There is added flexibility on an nForce 4 SLI motherboard, but this flexibility comes with some limitations. Today, NVIDIA sheds the shackles of the paddle selector and limited bandwidth with the new nForce 4 SLI X16 chipset.
In addition to the increased bandwidth and ease of use come quite a few extra niceties. Boards based on nForce 4 SLI X16 will have more I/O options on top of the added PCI Express bandwidth. The introduction of a new enthusiast part will also push prices down on existing products and NVIDIA will begin selling its current nForce4 SLI solution at mainstream prices. Aside from cheaper being better, this should increase adoption of the SLI platform giving the mainstream user some reason to care about SLI. With this also comes value for options like 6600 and 6200 SLI. Everything seems to be coming up roses for NVIDIA's dual GPU business right now with ATI's Crossfire still waiting in the wings.
With this introduction also comes quite a surprise from Dell. NVIDIA will be supplying core logic to the previously Intel-only volume computer manufacturer, making nForce4 SLI X16 the first non-Intel chipset for dudes to get in their Dells. This is quite a big announcement and will really help to boost NVIDIA's already successful chipset business. This announcement also gives some glimmer of hope for Dell as non-Intel hardware on the motherboard may mean that Dell is capable of making good decisions in the processor department as well. While it is unlikely that we will see AMD based Dell systems anytime soon, it's nice to know that the thin line between volume discounts and unfair business practices is clear enough to allow Dell to make the right choice for performance once in a while. At least, now one of their chipset vendors supports AMD as well as Intel.
Unfortunately, we don't yet have a board to test for performance numbers on the new configuration, but that won't stop us from talking about what's new under the hood.
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akugami - Monday, August 8, 2005 - link
This will boost video graphics performance as much as when 8x AGP came out over the then cutting edge 4x AGP. Which is to say slim to none. As others have stated, there is no known graphics card capable of fully utilizing the 8x AGP bus much less 16x PCI-Express bus. The Geforce 7800 doesn't come in AGP flavors so we don't know if it has a significant performance difference between 4x and 8x AGP.JarredWalton - Monday, August 8, 2005 - link
A few thoughts about the bandwidth increases now offered with the new chipset. First, for transfers from system RAM to the GPUs, this is completely useless. I also have to wonder what the link between the MCP and SPP is - it would have to have 8 GB/s of bandwidth to make the second X16 slot the same speed as the primary SPP slot. Hmmmm.... most I've heard of for a NB to SB interconnect is about 1 GB/s. Two HyperTransport channels running at 1000 MHz would provide enough bandwidth, but I seriously doubt that's present.Now, even if the NB to SB connection were fast enough, dual-channel PC3200 DDR only offers 6.4 GB/s of bandwidth - less than that of a single X16 slot. So SATA controllers sitting on X4 connections combined with two GPUs on X16 connections will now be possible, but the actual performance probably wouldn't be any different than SATA controllers on an X2 connection with two GPUs on X8 connections. Maybe we'll get quad-channel DDR2-667 RAM with socket M2 to make this a realizable performance boost? (/sarcasm)
There is a use case for it, though: GPGPU for one, and potentially SLI without the extra connector. Board to board SLI transfers over the internal X16 should be at least as fast as the proprietary connector I'd think. That last one is especially interesting, I think. If current SLI takes an X16 channel and breaks it into two X8 channels, how about a board with four X8 connections and four physical X16 slots for quad-GPU SLI? It wouldn't surprise me at all to find that NVIDIA has a team working on that exact project.
As the article states, the biggest deal about this launch for gamers is that prices will drop on SLI boards. Maybe then I'll be able to stomach recommending SLI for a mid-range system. The even bigger deal for NVIDIA is that they now have an "in" with Dell. THAT is freaking huge! I don't think Dell actually sells that many XPS systems, but then I don't think that many Intel SLI setups have been purchased as a whole. Dell has marketing power, and they WILL find ways to convince people to buy Intel SLI PCs.
ceefka - Tuesday, August 9, 2005 - link
4 graphics cards? Looks like the PC is turning into a gaming console and losing its general purpose, unless you're a stock broker maybe ;-)Having this abundance of PCI-E lanes looks like a step to abandon PCI(-X). The nF4 boards have issues with professional soundcards on the PCI-bus. It is a pity all these gadgets and extra performance have downgraded the PCI-bus instead of enhancing it.
I believe it is time for cardmanufactureres to develop more PCI-E based cards. It seems like chipset manufacturers aren't willing to spend the time to preserve good bandwith for the old PCI-bus.
ChiefNutz - Monday, August 8, 2005 - link
Nvidia Graphic cards communicate through their "crossbar" on the top of the cards, so, even having just 1 HT link between SB & NB wouldn't be that big of a deal. I don't think that it would saturate the HT link either, due to the crossbar. But this setup would be nice in a system if they got rid of the 16x crap and just gave you the straight channels like the 2200pro and 2250, like a 8x or 2 4x slots like that.What I really want to know is will they now support raid 5 on a non NForce-Pro AMD system?? Intel edition has it and so does the 2200pro? where is the NON-ECC love!
JarredWalton - Monday, August 8, 2005 - link
Yes, they have their crossbar controller, but they still get information from the CPU and main memory. If you ignore the GPU to CPU/RAM via PCIe bus communications, then there is no difference whatsoever between SLI X8 and SLI X16. (Which is likely the case anyway.)RAID 5 appears to be coming with the nForce4 SLI X16 chipsets to both platforms. We just neglected to mention it:
afrost - Monday, August 8, 2005 - link
So now nforce boards will have two really hot chips that need loud little fans or elaborate heat pipes? I hope that with this new generation of nforce chips they figure out a way to cut down some of the heat output. The nForce 3 was perfectly fine but the 4 gets toasty.This is one of the main reason that I am looking forward to the ATI boards....I like passive chipset coolers.
Anton74 - Monday, August 8, 2005 - link
Perhaps now that it is a 2 chip solution rather than 1, each of the chips will run a bit cooler than if they were combined, hopefully allowing for simple passive cooling with good (aftermarket) heatsinks like that blue Zalman one, the ZM-NB47J. As long as they don't put those chips in un-strategic places...Gerbil333 - Tuesday, August 9, 2005 - link
That was my first thought when I read this. The current nF4 chips run way too hot. I really hope the new two chip design runs cooler.virtualrain - Monday, August 8, 2005 - link
Doesn't this solution completely do away with the need to either open the case and flip the switch to enable SLI or select it electronically (i.e. ASUS A8N-SLI Premium) and reboot?If so, that's a positive move even if there is no performance gain.
One of the appeals of ATI's crossfire solution is the expanded flexibility and ease-of-use. I think this even's that part of the playing field somewhat.
Calin - Tuesday, August 9, 2005 - link
As I remember, old NVIDIA SLI had that switch to distribute the PCI-E lines in 1x16 (a single usable slot) or 2x8 (two usable slots). There might have been some kind of extra connections to have a single x16 slot and one 4x slot (20 PCI-E lines used) or two x8 slots (16 PCI-E lines used, and 4 unused).It would be great to be able to change the SLI/non-SLI configuration from drivers.