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Thread: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please




  1. #1
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    Feb 2009
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    Unhappy X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    Hi there, rather than bump any several-month-old threads, I thought I'd post a fresh new topic.
    I'm using an E0 stepping Q9550 with the above, and my overclocking ability is, disappointing, to say the least.
    I used to own an X38-DS4 and ran at 430*8.5 = 3.65Ghz on a 24/7 basis with no stability issues and could push to the 455FSB wall of the X38 chipset, and at least manage benchmark runs, though the overall stability was questionable. The reason I upgraded to the X48-DS5 was that when I purchased the second HD4870X2 card, I would get GPU shutdowns in games - i.e. graphics fans rise to half speed, monitor goes into standby, and system has to be reset manually, this regardless of my CPU overclock.

    After getting the DS5, this still happens whenever the system is overclocked (but not at stock), unless I set the G(MCH) voltage to exactly +0.1V. Leave it on auto and the black screens return, raise it any higher and the black screens return. As a precaution I have also raised the PCIe voltage by 0.1V.
    If anyone could explain this I would be very grateful, ATI insist it's a PSU issue but the fact it happens with a BeQuiet DarkPower Pro 850W, Zalman ZM850-HP AND a Corsair HX 1000W make me think it's the board (Both cards perform perfectly on their own)

    I should explain, if I'm using a voltage that causes me black screens, the cards will even shut down when I'm in the BIOS, adjusting settings, sometimes so soon I don't even have time to go in, disable the OC and reset.

    So that's one gripe, but the main one is that I was expecting the 200 X48-DS5 to be a better overclocker than the X38-DS4 that barely cost half that much. In fact, it's worse, considerably. 430x8.5 is my absolute limit, while it runs stable as before, even using as high as 445 will cause the system to BSOD loading windows. 455 which could run in windows for hours with the X38 won't even POST with the X48 board , it reboots at the memory test.

    Now, I'm unfamiliar with X48 overclocking, and I'm told I should be looking at PLL voltages, but I don't see them in the BIOS.

    Any help would be appreciated, or if I must hear it, anyone telling me I've got a lemon board that should be RMA'ed.

    Thanks in advance

    Edit:
    I'm using 2x2GB Corsair XMS2 Dominator PC2-8500, without the fans, as they don't seem to get too hot without them.
    CPU cooler is Thermalright Ultra-120A with Nexus 120mm fan at 800rpm.
    Last edited by samuelmorris; 02-15-2009 at 03:46 PM.

  2. #2
    Join Date
    Sep 2008
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    990

    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    I ahve no Crossfire experience, but please try to overclock with just one card, to see if that improves the situation. We need to single out the problem and to know whether CF has something to do with it is important.

    The X38 and X48 chipsets are virtually identical btw and and so is the EX 38 (but not the X38) and X48 series.


  3. #3
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    Feb 2009
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    A little update - I've managed to get into windows at 3.87Ghz (455x8.5) by:

    CPU/PCIEX Clock Driving control: 800mV
    CPU Clock Skew Control: 100ps
    PCIE overvoltage: +0.15V:
    FSB Termination overvoltage: +0.25V
    G(MCH) overvoltage: +0.25V
    GTLREFs: both -3%
    CPU voltage: 1.400V

    Raising the NB volts as usual caused the graphics blackscreening but I appear to have solved this by using a deafening 2400rpm Silverstone FM121 at full speed as my side fan.

    At these settings the system seems to be stable for the short term, 3DMark06 completed without incident anyway. The clue here seems either to be adding those clock skew control settings, or perhaps more likely, nudging the chipset voltage up. I've every temptation to keep going now I've brute forced 20C off my NB temps with this crazy fan, but I have the nagging feeling I'm going to be cutting the life of this board down to weeks if I go any further.
    Can anyone lay down some boundaries for this? I know large VTT and PLL are big nonos for longevity, but what about the plain old MCH volts?

  4. #4
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    Hi Nickel, thanks for the response, while I admit CF could be a problem when in windows, the fact is, it activates when the Windows logon screen appears, until then it's just two separate cards as far as the system is concerned, and it's pre-windows that the stability issues pop up. With just one card, I could get 3.87, but no further, using the aforementioned settings but +0.1V on the MCH, and not having changed the Skew controls.

  5. #5
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    Glad it works!

    Ok, the fact that a fan on the NB helps indicates that CF causes more strain on the NB and it overheated. That's why more than +0.1V MCH Core caused it to become unstable according to your first post. Maybe get a small 40mm fan and put it on the NB, teh 4870X2s are so loud you likely won't notice it anyway.

    I don't have any experience with the following two:

    CPU/PCIEX Clock Driving control: 800mV
    CPU Clock Skew Control: 100ps

    CPU clock skew is supposed to help though according to clunk.org.uk
    What is the dault value for CPU/PCIEX Clock Driving control on you board? On P45 it seems to be 900mV...
    Gigabyte GA-EP45-UD3R Living Review - Clunk's Forums.

    I don't really know what it does though, you should do some research as to what it actually is.


  6. #6
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    Indeed, the clock skews still mystify me as I don't know if they're actually helping, I just copied them from a guy who got an X48-DQ6 to 4Ghz with my CPU (but he used +0.475V on the chipset, which is a bit rich for my taste)
    I've also no idea how to find out what the defaults are, it's hard enough working out what the defaults are for voltage.

    I tried to get to 470FSB, and raised the MCH volts to +0.35, not only was I met with a bluescreen (101, but hardly relevant, as its obvious what caused it), but also the blackscreens came back, even with the full speed side fan.
    I've come to think that the only way of pulling 4Ghz off on this board is indeed to use the insane voltage this guy at overclock.net used. In addition, he only used a single 8800GT, not two dual-GPU cards.
    As much as I want to put a fan on the NB, the extra cooling is needed every bit as much at idle as it is at load - and I do care about idle noise. My PSU and GPUs are very quiet at idle, a 40mm fan on the chipset would ruin that.

  7. #7
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    Sep 2008
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    You could try to get rid of the heatpipe and get a Thermalright HR05 for the NB and a HR09 /chekc the compatability list on their website!) for the mosfets. The SB will be allright with any low profile chipset heatsink.

    Or try to undervolt a 40mm fan, even a little airflow may greatly help.


  8. #8
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    Thermalright's site is a bit confusing about that - it lists the HR-05/IFX, SLI/IFX being compatible with both the north and southbridge, but just says 'not compatible' with regard to VRMs with the comment 'you need to remove stock heat pipe' - does that refer to the chipset, or does that mean you can use an HR-09 if you take the whole Gigabyte assembly off (which should surely be obvious)?

    I could indeed try undervolting the fan, but I'm not sure it'll do that much good on the basis that even the 2400rpm 120mm side fan isn't enough once I push past +0.3V.

  9. #9
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    Actually the first thing you should do is remove the heatpipe, clean the NB and apply some proper thermal paste to it, that can improve NB temps greatly.

    The "you need to remove stock heatpipe" disclaimer refers to the fact that you need to remove the ehatpipe to change any one cooler.
    I just noticed that there is no HR09 for your board, I thought they had one...

    Watercooling may be an option, there are plenty of blocks for X48 mosfets out there, but a CPU, NB and Mosfet solution isn't all that cheap.

    You can also cut the heatpipe and change only the NB cooler, but you're unlikely to be able to RMA the board after that...


  10. #10
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    Feb 2009
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    Default Re: X48-DS5, Q9550, 2xHD4870X2s - Overclocking advice please

    Yeah, I'll pass on butchering the stock cooler for a 200 board thanks... :P
    Changing the TIM is something I'll be doing soon enough, but short of that, not really much else I can do, I'm not willing to settle for watercooling, it's too needy and too expensive.

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