Original Link: https://www.anandtech.com/show/2400
NVIDIA 780i: Evolution Plus Triple SLI
by Wesley Fink on December 17, 2007 9:00 AM EST- Posted in
- CPUs
NVIDIA brought editors together at their corporate headquarters in late October to discuss the launch of nForce 780i, 8800GT, 8800M, 3-Way SLI, and ESA. It certainly appeared at that time that all those new technologies would launch in early November. Unfortunately, there were early problems with 780i and the Intel Penryn processor, and NVIDIA delayed 780i until the Penryn compatibility issues could be resolved.
Since 780i is 680i with an added chip to support PCI 2.0 and two more x16 PCIe ports, it looked for a while as if NVIDIA might actually skip the 780i launch and wait until the DDR3 generation for a new chipset launch. Refinements for Penryn compatibility were completed and NVIDIA worked with Intel for Penryn family (Yorkfield quad-core and Wolfdale dual-core) compatibility certification.
Now, almost two months later, today is the official launch day of the 780i and 750i chipset. This is not just a paper launch, since 780i motherboards are available, or will be very soon, from NVIDIA launch partners XFX and EVGA. NVIDIA calls this the launch of the NVIDIA nForce 700i Series.
From a launch perspective, it is important to understand that 780i is not a new chipset. NVIDIA has said in their press releases, "The NVIDIA nForce 780i SLI MCP is built on TSMC's 90nm process technology, and contains the same micro-architecture as the NVIDIA nForce 680i SLI MCP. However, 780i SLI was designed with a high performance interface to be paired with nForce 200 to provide next-generation PCI Express 2.0 bus capabilities."
NVIDIA added 1333MHz bus support to the 680i chipset in June, as you saw in our review NVIDIA 680i SLI: Official 1333MHz FSB CPU Support Arrives. Other features are refinements to the 680i chipset that have been added as the 680i evolved in the marketplace. The only truly new specifications are features related to the added NVIDIA nForce 200. Compared to the 680i/650i chipset, the nForce 200 adds 32 lanes that are PCI Express 2.0 compatible.
With the addition of the nForce 200, this NVIDIA chipset can now provide the new feature of 3-way SLI. We will take a closer look at Triple SLI in another review today. If you are interested in the additional performance, a third NVIDIA graphics card can add to gaming performance in certain situations, and you will be interested in those test results.
The other new feature announced with the 700i series is ESA, which allows the NVIDIA chipset and software to control many system components. This technology is discussed in NVIDIA Introduces ESA - Enthusiast System Architecture. Testing has just begun on a system with a full complement of ESA devices. A review will be posted as soon as testing is complete on how ESA actually works in a system, and the potential benefit of ESA as a system control center for the computer enthusiast. In good news for 680i owners, NVIDIA now tells us that ESA will be backwards compatible with 680i after all. We will provide updated information on how that actually works in the upcoming ESA system review.
Since the 780i is the same chipset as 680i with the added nForce 200 for PCIe 2.0 and Triple SLI, we do not really expect any performance advantage for the 780i compared to the 680i under the same test conditions. We did a couple of quick general performance benchmarks just as a sanity check. The real performance advantage should be in with the new 3-Way SLI feature. We will cover this in our Triple SLI review, which examines the potential added gaming performance available with 3-way SLI. We will discuss the architecture and motherboards available at launch in this article.
nForce 780i Platform
NVIDIA targets their top chipset at the "hard-core overclocker", and each new generation adds more features that cater to the computer enthusiast. The nForce 780i tops the product line and defines state-of-the-art for NVIDIA chipsets.
The 780i is the 680i chipset with an added nForce 200 chip to support 32 lanes of PCIe 2.0 capabilities. This allows the addition of 3-way PCIe with three x16 PCIe slots. It is important to point out that while there are three x16 slots for 3-way SLI, only two of the x16 slots are PCIe 2.0 compliant. The third x16 slot is derived from the nForce 570 MCP (identified in the block diagram as the 780i SLI MCP), which is an older chip that is not PCIe 2.0 compliant.
The nForce 200 is a PCI Express switch chip with one upstream port and up to four downstream ports. The 780i provides two x16 PCIe 2.0 downstream ports, which can also be configured as four x8 PCI Express 2.0 ports. The interface between the 200 chip and the 780i SLI SPP provides a maximum bandwidth of 4.5 GT/s per link, which is enough bandwidth to provide full performance of PCI Express 2.0 Graphics cards like the 8800GT.
In the launch review for the 680i chipset we saw the 680i with a total of 46 PCIe lanes, distributed as 18 with the SPP and 28 with the MCP. As you can see in the above diagram 780i has 62 PCIe lanes, distributed as the same 28 lanes on the MCP, just two lanes on the SPP, and 32 PCIe 2.0 lanes on the nForce 200 chip. The extra 16 PCIe lanes on the 680i SPP provide communication with the nForce 200 chip. The bottom line is the 780i picks up an extra "full" x16 PCIe slot. The PCIe lane count, ports, and device support are otherwise the same as the 680i chipset.
With the addition of 3-way SLI as a new 780i chipset feature, NVIDIA believes hard-core gamers and performance enthusiasts will migrate to the 780i motherboards. We will examine Triple SLI performance in a separate review that you will definitely want to read, particularly if you are a hard-core gamer.
nForce 750i Platform
The lower-priced 700i board is the 750i, an update to the current 650i chipset.
The 650i SLI has 18 PCIe lanes, which come from the SPP; the MCP does not supply any PCIe lanes. 750i follows the same pattern as 780i, with the SPP using the 16 PCIe lanes to communicate with the nForce 200 chip. The nForce 200 chip provides PCIe 2.0 compliant slots, but it is configured as one x16 slot and one x8 slot, where the 780i provides two x16 slots off the 200 chip.
This is an improvement over the 650i, which could be one x16 slot or two x8 slots. However, it is apparently not possible to split the 750i into three x8 PCIe 2.0 slots, for example, as the 780i can split into four x8 PCIe slots. Except for the added x8 PCIe 2.0 slot the port, slot and peripheral count remains the same as the 650i. 750i motherboards will not ship until January, so we will not have hands-on performance results for another 4-6 weeks.
Test Setup
There should be no real difference in performance results between the 680i and 780i provided everything is the same on both test platforms. Certainly, 3-way SLI could make a difference, and we will test this in the Triple SLI review also published at AnandTech today. A single 8800GTX tested with the same CPU and memory on both chipsets will likely perform the same.
However, many times what should be the same turns out to be different when we run actual tests. Just to make sure, we will run several general performance benchmarks on both the 780i and 680i chipsets and compare the results.
Performance Test Configuration | |
Processor | Intel Core 2 Duo
QX6850 (Quad-core, 3.0GHz, 2x4MB Unified Cache) |
RAM | OCZ Reaper PC2-9200
(2x1GB) Tested at DDR2-800 3-3-3 2.2V |
Hard Drive | Western Digital Raptor
150GB 10,000RPM SATA 16MB Buffer |
Video Cards | 1 x MSI 8800GTX |
CPU Cooling | Tuniq Tower 120 |
Power Supply | Corsair HX620W |
Motherboards | EVGA 780i SLI EVGA 680i SLI |
Operating System | Windows Vista Ultimate 64-Bit |
General System Performance
The PCMark05 benchmark, developed by Futuremark, is useful for determining overall system performance for the typical home computing user. This tool provides both system and component level benchmarking results utilizing subsets of real world applications or programs. The test is useful for providing comparative results across a broad array of GPU, CPU, hard disk, and memory configurations along with multithreading results. In this sense, we consider the PCMark benchmark to be both synthetic and real world in nature while providing consistency in our benchmark results.
As expected, the performance difference between 780i and 680i is less than 1%, which is well within the confidence levels of this benchmark. Essentially both chipsets perform the same.
General Graphics Performance
The 3DMark series of benchmarks from Futuremark are among the most widely used tools for benchmark reporting and comparisons. Although the benchmarks are very useful for providing apple to apple comparisons across a broad array of GPU and CPU configurations they are not a substitute for actual application and gaming benchmarks. In this sense, we consider the 3DMark benchmarks to be purely synthetic in nature but still valuable for providing consistent measurements of performance.
The later 3DMark tests, such as 3DMark05, are almost entirely influenced by the GPU under test, though CPU performance plays a larger role in 3DMark06. Results should be extremely close in this instance since we use the same graphics card for testing on both systems. 3DMark01 is still widely used because it is a useful overall system performance test. System, CPU, and memory configurations affect results far more than in later 3DMark benchmarks.
3DMark06 results are all but identical, while 3Dmark01 shows performance results within about half a percent. Performance in these general graphics benchmarks is therefore the same.
Rendering Performance
The CINEBENCH 9.5 benchmark heavily stresses the CPU subsystem while performing graphics modeling and rendering. We utilize the standard benchmark demos in each program along with the default settings. CINEBENCH 9.5 features two different benchmarks with one test utilizing a single core and the second test showcasing the power of multiple cores in rendering the benchmark image. We use the multi-core benchmark to compare the 780i and 680i.
Results in the SMP rendering tests are the same for the 680i and 780i.
Tests with these four general performance benchmarks confirm that the performance of the 780i and 680i is essentially the same when using equivalent systems. This is what we expected given the fact that NVIDIA clearly states there is no change in the micro-architecture of the 780i compared to the 680i.
Recent graphics testing has already established that current video cards do not even come close to saturating the current PCIe 1.1 bus. Future video cards and applications will be more demanding, but it will likely be some time before we see a measurable performance advantage with PCIe 2.0.
Launch Motherboards
At launch, two 780i motherboards are available from NVIDIA partners. As is often the case with new NVIDIA chipsets, both boards follow the NVIDIA reference board layout.
The XFX 780i will certainly stand out on a shelf. The package is almost twice the thickness of a normal motherboard.
The motherboard itself is remarkably similar to the NVIDIA 680i, which should not come as a surprise to anyone.
Ports and port layout for the XFX 780i are the same as the earlier 680i reference board.
EVGA has also introduced a 780i motherboard. EVGA uses more standard motherboard packaging, with a very green NVIDIA theme.
As you can see in the photo if would be difficult to tell the EVGA from the XFX board were it not for the EVGA logo.
Changes Compared to 680i
While the boards may look like 680i boards, there have been a few changes made to the reference design. We complained about the location of the front panel header, as did almost every site that reviewed the 680i. NVIDIA listened and they have now moved the front panel (power on, reset, LED, HD) connector block to a more traditional and easy to work with location.
NVIDIA also added a CPU thermal diode LED nest to the CPU fan pins. This turns red when the board detects abnormal CPU heat. This is not particularly useful once a board is in a case, but for test bench overclocking it is a nice feature. Windowed case users may also find it a useful addition.
Finally, NVIDIA has revised the heatpipe design to work better and keep the system a bit cooler. An optional fan is still included, and it is needed for serious overclocking. Those who value quiet can run the board without any active cooling at stock speeds.
Availability
Final Words
When we first saw the 780i chipset in late October it was clear that the new chipset was basically the same 680i two chip micro-architecture with an added nForce 200 chip to provide two x16 PCIe 2.0 compliant graphics slots. 680i already supports 1333FSB bus and DDR2-1200, so this wasn't new. However, there were several intriguing new features such as support for the new 45nm Penryn chips from Intel, 3-way SLI to boost gaming performance using three NVIDIA graphics cards, and the introduction of ESA to give enthusiasts the ability to custom control all the major components of their system. These interesting features provided a bit of justification for the upgrade to 780i.
Then NVIDIA delayed the 700i series for about six weeks as rumors flew that Penryn would not work properly with 780i, at least in the quad-core flavor. The talk was that NVIDIA was respinning the chipset to fix compatibility issues. NVIDIA now tells us that the issue was a change in the final release of Penryn that required a rework of some of the board circuitry. The chipsets themselves, both 780i and 680i, are said to be perfectly capable of supporting Penryn if used on a modified board. It now appears a complete fix cannot be made with just a BIOS update for 680i; it is possible a BIOS update will allow dual-core Wolfdale to work as it should, but not quad-core Yorkfield. We will leave the official word for this with NVIDIA and their board partners.
At any rate, somewhere along the way to the fix for Penryn, the new features of 780i became not so exclusive. First, NVIDIA now tells us that 680i can also support Penryn on a reworked motherboard if the manufacturer chooses to implement it. We also hear that most manufacturers are choosing to move to 780i for their Penryn support, although a few manufactures will release an updated 680i board that will fully support Penryn flavors. Last Thursday 3-way SLI launched (but not 780i), and we learned that 680i could also support 3-way SLI. This support is via two x16 slots and an x8 slot, and none of the slots are PCIe 2.0, but Triple SLI will still run on 680i. Strike down another feature we thought was exclusive to 780i. Finally, in the last few days we learned that ESA, NVIDIA's interesting new Enthusiast System Architecture control standard, would also work on the 680i chipset. At this point, we are left to ask what then is truly unique about 780i.
The answer appears to be three x16 PCIe slots instead of x16, x16, x8 with two of the slots (but not all three) being PCIe 2.0 compliant. This seems to be a tremendously small advantage, even for a chipset that is clearly more evolutionary than revolutionary. Our own tests confirm what NVIDIA has already told us, and that is that performance of the 780i under the same test conditions is the same as the 680i chipset. There is, however, one big advantage for 780i. You can be sure, with 780i, that your motherboard will support Penryn. While the 680i might support Wolfdale with a BIOS update, you will need a new board to run Yorkfield. If you are going to have to buy a new NVIDIA board, you might as well buy the 780i.
Again, we are taking a closer look at 3-way SLI on the 780i so look for our test results on whether the 3-Way performance with three x16 slots will make a difference for you later today. You will also see a review shortly that will examine the overclocking capabilities of the 780i. We are still excited about ESA, and we are hard at work on a review of an ESA system with a selection of current ESA certified components. We are interested to see what real impact the ability to control peripherals other than the motherboard will have on system performance.
To be blunt, there is almost nothing new about 780i. It now turns out 680i does all the same tricks except supporting three x16 PCIe slots (680i supports x16, x16, x8) with two being PCIe 2.0 compliant. However, you do get assurance with 780i that you are getting a new NVIDIA motherboard certified by Intel to support Penryn (Wolfdale and Yorkfield). You do not get that assurance when you purchase a current 680i chipset motherboard.
We like the new features from NVIDIA that we first saw in late October with 780i. The fact that virtually all of these new features also run on 680i just means that they are not exclusive, which is good news for current 680i owners. Whether 3-way SLI on three x16 PCIe slots, ESA control, or Penryn compatibility are features you want is something individuals will need to examine for how they fit their vision of a great computer system.