Quad-Core Overclocking, continued

Approximate VTT values and FSB ranges

VTT = 1.2V - 1.3V = Up to 400 FSB

VTT= 1.4V - 1.55V = 420-440FSB

VTT=1.6V (~1.58 actual) = 440-475FSB


A few notes on applying values from the VTT/GTL table


1) Fig 1. The first column shows BIOS and actual measured voltages for VTT (first value is measured VTT), the value in brackets is the voltage that must be applied in the BIOS to obtain the measured value. As can be seen, there is a small offset between the BIOS setting of VTT and the actual DMM measured onboard voltage. An average representative figure has been used for the tables. We have found a general variance on boards either 0.1V above or below these figures. Each motherboard will have different sweet spots for GTL values due to this small offset.

2) GTLs set to 66%-70% of VTT seem to be at the most effective point for "stable overclocking" of quad-core CPUs. The highlighted color bar in each VTT/GTL table shows the approximate 67% point of VTT and the corresponding numerical value that needs to be set in the BIOS. We recommend you choose a target FSB range (see the FSB/VTT ranges above) and use the according VTT/GTL scale starting with GTLs @ the 67% values of the applied VTT (the highlighted values in the tables).

The GTL scale voltage values themselves are changed as VTT voltages are raised or lowered by the user in the BIOS. It is necessary to follow the corresponding scale for the set VTT voltage, as looking at the scales above we can see that a level of offset is also applied to the numerical BIOS setting scale.

The 1.2 VTT GTL scale sets 80 GTL digits to a value of 0.80V; however, once VTT is increased to 1.3V the value of 80 GTL digits represents 0.855V. This shows the importance of having the above scales on hand so that we can pick the right values to use when we change VTT.

3) While there is not a universally applicable methodology for tuning GTLs to reach 450FSB+, please note the following:
  • The default BIOS VTT value is 1.2V and the GTL controls are "DISABLED" in the BIOS by default. Once "ENABLED" is selected the GTL values will automatically default to 110/110/110. These values DO NOT represent a 67% level of 1.2V VTT. Furthermore it is important not to leave this control disabled at any time while tweaking VTT/GTL settings, even if the 67% mark happens to fall at 110/110/110. (Set them manually!) You will need to readjust the GTLs to represent the correct percentage by using the appropriate scale.
  • Our tests revealed that CPU load testing failures generally occurred when CPU temperatures exceeded 65C or so. Over 65C it becomes ever more difficult to tune GTL voltages as there is always some uncertainty pertaining to the cause of a CPU core failure: Was it temperature or VTT/GTL related?
  • Use active cooling on the Northbridge. Load temps need to remain under 45C to ensure stability in Prime type tests.
  • VNB needs to be around 1.61V to 1.65V for 450FSB upwards if using the 266 strap with a Performance Level of 6, which is recommended as memory speed performance per volt is at its best for 2GB. Using 4GB configurations, the 1333/800 strap/divider with a Performance level of 7 works very well.

Quad-Core Overclocking Quad-Core, Part 3
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  • retrospooty - Sunday, October 21, 2007 - link

    Not really. Check this memory test here at AT. http://www.anandtech.com/memory/showdoc.aspx?i=312...">http://www.anandtech.com/memory/showdoc.aspx?i=312...

    At DDR 2000 at 6X500 CPU the best sisoft standard memory score for DDR3 is 9138 at DDR3 2000 8-7-6-18 ... I get 8871 with my DDR2 1000mhz at 4-4-4-10 with a similar setup on the DFI P35 mobo. DDR3 even at a highly overclocked 2000mhz is hardly faster than DDR2 at 1000 now. I am not going to go to DDR3 until Nehalem is cheap, and DDR3 latency is lower and cheap, 2 more years out.

    And PCI-E 2.0 is not going to help for a long time. Like with PCI to AGP, and AGP to PCI-E there is no improvement at all right off the bat. The graphic bus standard is always WAY ahead of the actual cards need for it, 1-2 years at least. We are not even utilizing PCI-E 8x, much less 16x, not even with dual 8800GTX's. Also , PCI-E 2.0 is backward compatible, so I I get the latest greatest Graphic card next year (whatever it is) it will be PCI-E 2.0, but will work fine on PCI-E 1 motherboards.
  • Raja Gill - Thursday, October 18, 2007 - link

    It's one of those things in life, despite having no real logic to it, 'tweaking' actually has a market. DFI took a risk, while this segment does not guarantee large sale volumes, some of the return is made up in a higher profit margin. Without DFI around, some of the more pioneering BIOS options (that actually are of use to Joe blow due to Intel's binning strategy), would never filter thru to other boards. The asking price is high, both Gary and myself recognised this. It has to be said that those who have paid the premium have generally not been dissapointed. In terms of the cascade results, yes, boardss like this and Asus's ROG line are used by the benchmarking community to chase big records, again this is a growing community who pays high dollar for every last drop of performance. We are aiming to satisfy a slightly wider audience with the performance board reviews, by looking at how they will be used, and help out with settings by spending long hours exploring the BIOS functions ourselves, still trying to give a balanced view for JB and some insight to help the benchmarkers decide if the board fits their needs... The bios's on so many of these boards are getting more complex, we hope those who buy the boards can use some of the settings we provide to get a base to work from, (if they need it)..

    If there's anything else you would like to see added, please let us know....

    regards
    Raja
  • Jodiuh - Friday, October 19, 2007 - link

    SCREW THEM ALL! I've been drinking and still managed this in under 2 hours.

    http://img.photobucket.com/albums/v212/jodiuh/DFI%...">http://img.photobucket.com/albums/v212/...0UT%20P3...

    Sure I've been able to achieve good results w/ lowly air on the Giga DS3, Asus P5B, DFI Dark, and Abit IP35, but this board:

    1. makes oc fun
    2. great layout (usb ports towards the front where they should be, shame Abit)
    3. great stock cooling, especially for air
    4. excellent bios
    5. did I mention speed drunk oc? (beer, then 50mhz on the bus)

    It's truly a great game. And for about $260, it's a steal. There's no other board that offers this much pleasure. Sure it's $, but then didn't most of you pay $320 for your 6600's? :D
  • Avalon - Friday, October 19, 2007 - link

    Any drunk monkey could OC a decent C2D to 3.5Ghz. I've had plenty of fun OC'ing on my $90 Gigabyte P35 DS3L, which also has a great layout and decent BIOS. It's no DFI, but it gets the job done for $160 less, which is enough money for me to buy a decent video card, 4GB of RAM, 750GB of hard drive space, etc...

    Don't get me wrong, DFI is by far my favorite motherboard company, and their BIOS tweaking is the best available. However, I will NEVER consider a $260 board a "steal" when the only thing I'll get out of it over a significantly cheaper board is that I have more settings to play with if I feel bored. Fortunately, when I get bored, I load up a game, instead.
  • cmdrdredd - Saturday, October 20, 2007 - link

    Avalon hit it right on the head. Any decent C2D can do over 3.2Ghz and some up close to 4Ghz with proper cooling on $90 boards. There is absolutely NO reason to buy a $260 board this late to market. Not to mention that it is also slower than boards which retail for less money in this review at the settings used.

    The number of people actually willing to and wanting to use 550Mhz+ FSB is too small to matter.

    /end
  • Jodiuh - Tuesday, October 23, 2007 - link

    Most of the 965 board's are a crap shoot for 500fsb, but the 2 p35's I've used had no qualms about this. It's not just getting the OC for me tho. I needed a board that:

    -doesn't look like rainbow brite exploded on it (Gigabyte DS3)
    -doesn't use an AMI bios, hits 500+ FSB easily (Asus P5B Deluxe)
    -doesn't crackle (DFI P965-S, Abit IP35 Pro)
    -isn't NV (EVGA 680i)

    -has usb ports, front panel header, and SATA ports in the far right of the board
    -and of course the great stock cooling (uses nuts/bolts), excellent bios, and stable voltages add to the package

    There's just no other non-Asus board that did all that right now. Paying another $70 for the extras isn't an issue for a hobbyist that plays w/ his rig.
  • Acanthus - Friday, October 19, 2007 - link

    Yes, we did.

    And on quad cores, this board does no better than other boards much cheaper than itself.

    I am not here to bash DFI, they make great stuff.

    The price of admission is too high for this board for quad overclocking from the results i've seen. The FSB limitation appears to be the G0 quads themselves, they all seem to top out at 470-510fsb anyway. The Asus P5K and Gigabyte P35 DQ6 both easily do those speeds on unmodified boards.
  • customcoms - Thursday, October 18, 2007 - link

    Thanks anandtech for providing an overclocking article TRULY worth reading! We needed a motherboard review like this when DFI's original nForce4 boards came out-trying to figure out every bios option, while fun and rewarding, is a very very time consuming process.

    Its one thing for a reviewer to claim "this board is capable of 500+ fsb speeds" and another COMPLETELY for that reviewer to document virtually every step and every bios option they used to get to that speed. This review is along the lines of the user reviews I normally turn to to verify the components I am interested work as advertised. While the cascade cooling results and extreme price of this board could have been left out, it is good to see a reviewer actually using the hardware in the environment a $300 (or $260, or any board over $200 imo) motherboard is going to be used in.
  • Jodiuh - Thursday, October 18, 2007 - link

    It can be found for $260 from motherboardpro. Comes w/ a nice little LAN carrying harness too.
  • cmdrdredd - Thursday, October 18, 2007 - link

    Still too much money. As was said before, it still does not beat some of the boards which have been out for a long time. Sure it looks nice, but for the money spent here, you can buy more memory or the next step up in CPU if you go with a less expensive board.

    It's late, expensive, and does not have any magic that makes me say "it's better than anything else out there". Even the $90 IP35-E is a good match against this DFI board unless you have to or like to spend hours setting up the bios just so.

    It's nice, but like I said too little too late.

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