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Nvidia nForce 790i Ultra SLI

High-End Chipset Battle

x48 790i sli

Unlike Intel’s strict split between enthusiast products (X48) and the mainstream line (P35, G35), Nvidia has a more comprehensive chipset portfolio. The nForce 790i Ultra SLI, as reviewed in this article, is the top model for enthusiasts. The key feature for the Ultra version is SLI-ready memory support, which goes as high as DDR3-2000 speeds. None of the nForce 790i chipset versions supports DDR2, only DDR3. The nForce 790i SLI (non-Ultra) also supports SLI-ready memory, but only up to DDR3-1333. FSB1600 support is available with both 790i SLI versions.

Apart from the 790i flagships, the nForce models 680i and 780i also support three-way SLI (twin x16 PCI Express 2.0 plus one x16 PCI Express 1.0 slot), but these go with DDR2 memory instead of DDR3. There is SLI-ready memory support for automatic settings of ideal RAM clock speed and timings, which is limited to DDR2-1200 speed. Since there won’t be much faster DDR2 memory, this is more than adequate.

Finally, there is an nForce 750i SLI entry-level model, which is limited to two x8 PCI Express 2.0 slots, and so does not support three-way SLI. Memory support is restricted to DDR2-800, and SLI-ready memory is not supported. The nForce 750i has to live with one instead of two Gigabit LAN ports, and with only four instead of six SATA/300 plugs. While Intel is about to release single PCI Express 2.0 into the mainstream with P45 at Computex, the nForce 750i SLI is already there.

The block diagram of the 790i Ultra SLI is similar to that of Intel’s X48. The 790i Ultra SLI SPP northbridge (System Platform Processor) connects to the CPU via a 400 MHz quad data rate bus (FSB1600). There are as many as 62 PCI Express lanes; 2 x 16 of them are used by the northbridge to provide two x16 slots, the remainder are provided by the southbridge. The dual channel DDR3 memory controller supports speeds up to DDR3-2000, although SLI-ready DIMMs are necessary to have the system select ideal clock speeds and timings automatically.

While Intel connects its MCH and ICH via a 2 GB/s interface called the Direct Media Interface (DMI), Nvidia utilizes HyperTransport. This is particularly interesting since this is the interface that AMD uses to connect its processors and core logic — and it is being used on an Intel platform. However, HyperTransport is necessary, as the third x16 PCI Express slot for three-way SLI (using eight lanes) has to be provided by the Media and Communications Processor (MCP) southbridge.

The 790i Ultra SLI MCP provides two Gigabit Ethernet ports with teaming features, ten USB 2.0 ports (versus 12 ports with Intel), and six SATA/300 ports plus an UltraATA/133 channel for two legacy devices — Intel dropped support for parallel ATA with the introduction of the P35 chipset line. Nvidia also still supports up to five 32 bit PCI bus master slots for legacy expansion cards. High Definition audio is pretty much essential these days, so it doesn’t come as a surprise to find an appropriate unit on the MCP as well.

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  • 1 Hide
    dragoncyber , May 29, 2008 4:43 PM
    I went with the EVGA 790i Ultra intsead of the ASUS. They are both great boards, but the Asus was more expensive for the exact same feature set at the time.

    I am currently running this setup with the 790i:

    Q6600 @ 3.5ghz @ 1.32v Air Cooled (Prime Stable 4 instances/8hours)
    4Gb Corsair DDR3 XMS3 @ 7-7-7-20-1T @ 1.5v
    EVGA 790i Ultra w/FSB @ 1556 @ 1.40v Bios ver.P03
    (2)BFG 8800 GT's /SLI @ 710/1000/1600
    X-Fi Fatality Gamer Sound Card
    (4) Seagate 250Gb HDD's with 16mb Cache in RAID "0"
    (2) Samsung DVD-rw 20X
    1200 Watt Thermaltake Toughpower PSU

    3DMark Score: 18,900

    The Board runs great and is a better overclocker than my old 680i.
  • 0 Hide
    Anonymous , May 29, 2008 4:45 PM
    thanks for the article.
    but next board for me is going to be p45 chipset anyway.
  • 2 Hide
    frodbonzi , May 29, 2008 4:47 PM
    Unless you want SLI, x48 is the way to go (or P45 once it arrives).

    Honestly, just stick 1 9800gx2 in an x48 and you're set :) 
  • 4 Hide
    njalterio , May 29, 2008 4:58 PM
    Personally I think 790i and X48 are pretty much equal. Something tells me the writer of this article is a 790i/Nvidia fan boy with their conclusion regarding possible graphics card configurations. Yeah, there are only two PCIe x16 2.0 slots on the X48 but you could definitely put two 3870X2's in, which would be equivalent to four gpus, which would be considerably cheaper then the nvidia equivalent. Interesting how the author fails to mention that part.
  • 1 Hide
    tiganz , May 29, 2008 5:44 PM
    This article is inaccurate with regards to X48's DDR2 support , the X-48 definite DOES support DDR2

    Some examples of DDR2 X-48 boards :-

    GIGABYTE GA-X48-DS4 LGA 775 Intel X48 (DDR2)
    MSI X48C Platinum LGA 775 Intel X48 (DDR2&3 both supported on this one)
    DFI LP LT X48-T2R LGA 775 Intel X48
    GIGABYTE GA-X48-DQ6 LGA 775 Intel X48 (DDR2)

    the list goes on...

    It does however appear to be accurate stating the 790i doesnt support DDR2

    Still , im surprised that such an obvious error made it through to publication
  • 1 Hide
    pschmid , May 29, 2008 6:53 PM
    Technically, DDR2 can be supported. However, DDR2 support is up to the motherboard makers. Intel intends the X48 to work with DDR3. See:

  • 0 Hide
    reasonablevoice , May 29, 2008 8:16 PM
    I understand if you have the money and are in to computers spending 300+ on a motherboard is no big deal but for most people I suspect that is not happening. I use a gigabyte board, the ga-ep35c-ds3r, got it for about 150 USD and it works splendidly, its a good over clocker to boot. Don't get me wrong, if I were a rich bastard I'd have all the latest and greatest from a quad core extreme to 790i, etc. In a lot of cases I think we don't really need more than mainstream. I put together my current main use machine for around $900 and it does everything I need it to exceedingly well, the 3dMark06 score is just over 12,000. Not stratospheric but it lets me waste my life playing Oblivion all night.
  • 3 Hide
    The_Blood_Raven , May 29, 2008 8:21 PM
    Take my word, this article points out what I have come to realize from much better sources, all Intel chipsets out perform Nvidia's. This article is very biased towards Nvidia, though in all fairness the 790i platform is the first decent one from Nvidia. Funny how the author did not run into the common Vcore, or 45nm quadcore CPU problems this motherboard is plagued with. Also funny that they did not test the efficency of the PCIE 2.0 lanes, another place Nvidia has problems. Funny how there were no stand alone memory or memory overclocking benchmarks, not to mention GPU overclocking benchmarks. Another place this article fails to go, is to compare the heat production of these two boards, all these things are in Intel's favour. I'm not an Intel Fanboy, not at ALL, I just recently bought my first Intel CPU and I hate the fact that it came to it, but Intel makes some great chipsets and Nvidia truly does not. If nothing else just remember the X48 does not support DDR2 lie, and the painfully biased conclusion, it is all there just look for it. Thing is the X48 runs much stabler, produces less heat from the entire board including the N/S bridges and the capacitor placement is better, not to mention the fact that the X48 overclocks much better when coupled with custom cooling solutions. Oh well, THW I'll let this one past I suppose, I still love your forums!
  • 0 Hide
    weilin , May 29, 2008 8:55 PM
    interesting... it would appear that nVidia still has that RAID bug... I saw it in the 6x0 series and apparently its still around in the 7x0 series. Oh well, no cheap(er) large file server based on their boards for now... again...
  • 1 Hide
    alantlchan , May 29, 2008 9:00 PM
    Some more obvious errors on p.10

    1. 1st paragraph - PS/2 mouse connector should be PS/2 keyboard connector

    2. 2nd paragraph - X48 northbridge. X48 on 790i mobo?

    3. 3rd paragraph - ICH9 southbridge. ICH9 on 790i mobo?
  • 1 Hide
    Arbie , May 29, 2008 9:17 PM
    First, thanks very much for the review. I appreciate the effort Toms and others put into running the latest hardware for us and putting all those results together.

    I do ask that your motherboard reviews and reports include tests with 4GB of RAM. Would anyone even consider stopping at 2GB with a new "enthusiast" build (other than for a max OC screenshot)? And it should be 2x2GB since that's evidently more stable, and many people building expensive systems will want to at least keep the 8GB option open.

    So - do 2GB to see how high the mobos clock with that, but give us 4GB results too so I'll know which one works best the way I intend to use it. Your comparison review will be much more valuable.

  • 3 Hide
    non-distinct , May 29, 2008 11:11 PM
    The_Blood_Raven is spot on, but I'll be more blunt: Schmid's and Roos' journalistic integrity is tarnished by their failure to mention the numerous curious problems plagued by 790i chipset. A simple scan through the EVGA 790i forum would've removed any doubt that the chipset continues to have problems.
  • 0 Hide
    ocp_15k , May 30, 2008 10:54 AM
    I agree with njalterio, Nvidia must have a knife stuck up authors backside while he was writing the review.
  • 1 Hide
    JohnMD1022 , May 30, 2008 12:35 PM
    Please note that for those of us with aging eyes, who make use of Firefox's Ctrl + font enlargement feature, your pages do not render properly.
  • 0 Hide
    tiganz , May 30, 2008 1:33 PM

    The really bad thing is this article also contradicts this previous X-48 review done here at toms , which clearly shows DDR2 X-48 boards ;) 

    This previous review goes as far to say that X48 is just a higher binned X38 (in the same way that intel bins some Wolfdale CPU's as 8500's and others as 8400's) and the X-38's marketin...err i mean "specs" page states "official" DDR2 support..

    I also Agree with the comments made RE: the omission of the 3870X2 and CrossfireX as a viable route to provide a Quad or Triple GPU solution to the X-48 .

    Everything omitted from this article tends to paint the X48 in a bad light and tends to favor the nvidia chipset .

    Maybe this is an honest mistake but as a regular reader of toms guide for over 11 years I can honestly say ive never found any article on this site with so many glaring omissions...
  • 0 Hide
    tiganz , May 30, 2008 1:39 PM
    it seems the link didnt post above...heres the previous toms hardware X48 motherboard roundup/review,1781.html
  • 0 Hide
    evilakumagouki , May 30, 2008 2:22 PM
    The nForce models 680i and 780i also support three-way SLI (twin x16 PCI Express 2.0 plus one x16 PCI Express 1.0 slot) This sentence is wrong. The nForce 680i supports twin x16 PCI-E 1.0 and one x16 PCI Express 1.0 slot (with 8 lanes), so the 680i chipset has a total of 46 lanes.

    There is an nForce 750i SLI entry-level model, which is limited to two x8 PCI Express 2.0 slots, again, is wrong too: The nForce 750i has two X16 PCI-E 2.0 slots!!

    This article has a lot of mistakes and the author was unhappy.
  • 1 Hide
    butcher , May 30, 2008 3:20 PM
    the thing that would stop me buying a 790i mobo is the price

    there in the land of OZ you can get a x48dq6 for about AU$350 where as a striker extreme II is over AU $ 500

    and unless you want sli i dont really see the difference

    also with the asus you lose a pcie to that add on card thing
  • 0 Hide
    Fedor , May 30, 2008 7:18 PM
    I too think that the conclusion here is somewhat biased. Whilst reading the entire thing it was pretty obvious that for the most part Nvidia was just a tad behind the Intel chipset. However, I still think that the main point in the conclusion is very valid - for top top graphics, you have to go Nvidia because the ATI cards cannot compete at the high end. I'm not comparing price/performance here, just plain simple performance.

    One thing about the nvidia onboard RAID - it can be SUBSTANTIALLY improved:
  • -2 Hide
    anonymous x , May 31, 2008 4:38 AM
    790i for me!
    i like sli
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