SLI MSI 1070 MXM in P370EM... An adventure

Discussion in 'Sager and Clevo' started by bennyg, Jun 17, 2017.

  1. bennyg

    bennyg Notebook Deity

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    I have all displays working, internal display, and hdmi and dp out.

    Have not yet got a driver later than 375.70 working but I realised recently I was downloading the *notebook* nvidia driver packages instead of the *desktop* packages that the inf mods are for. So something else to try.
     
  2. thegh0sts

    thegh0sts Notebook Prophet

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    You'll have less issues with the P870DM-G + MSI 1070 combo. :D
     
  3. aarpcard

    aarpcard Notebook Deity

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    Wow. I think I know what my next mod is going to be. Do you forsee any potential issues with getting this to work with an internal EDP 4k panel?
     
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  4. bennyg

    bennyg Notebook Deity

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    I lack confidence in my ability to accurately repin the w230ss qhd cable sitting in the draw... that's my issue. I think the 30pin edp is wired the same across all the p370 refreshes
     
  5. otis01990

    otis01990 Newbie

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    Hi everyone!
    Bennyg,you've done really great job!) If you can,contact me ...I got a little problem with my 1070m and one of your photos can save me ^_^[​IMG]
    Need name of this component,which is bobled on my photo....
     
    Last edited: Oct 10, 2017
  6. Meaker@Sager

    Meaker@Sager Company Representative

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    What happened to it?
     
  7. otis01990

    otis01990 Newbie

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    Suddenly laptop reported about crash of video driver and after reboot there was only one GPU in device manager. After disassambling i've found this thing.
     
  8. senso

    senso Notebook Enthusiast

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    Taobao card, or some other source?

    I kinda want to jump to a 1070, taobao is a bit cheaper, but warranty or even assurance that is not dead is not great, and from ebay, its 1000€ :(
     
  9. bennyg

    bennyg Notebook Deity

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    I'll grab a super close up pic for you this weekend. I have to reflash the vBIOS back to the stock vortex one, literally no other driver or mod I've tried other than the MSI 375.70 package works. UEFI made no difference, god dammit reinstalling Windows (after converting storage to GPT) is such a hassle.

    Got my hands on AOTS and there's something seriously bottlenecking SLI(DX11)/mGPU(DX12), the GPUs sit on about 40-50% utilisation even downclocking themselves, and get around the same fps as a single 1070. The AOTS benchmark util says its >99% GPU limited (compared to 100.0% in single 1070).

    One thing I noticed in GPUz is in the NVIDIA SLI field at the bottom it says "high-bandwidth", is this normal for an old SLI cable dating back to the Fermi era?
     
  10. aarpcard

    aarpcard Notebook Deity

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    I've wondered about this since the Pascal laptop cards came out. They only have 1 SLI connector per card (and it is the same connector used on legacy gpu's), so they are not using a double bandwidth SLI bridge.

    GPU-Z reporting "High bandwidth" could simply mean that it's detected a SLI Pascal configuration and it interprets that as meaning it must be High Bandwidth; i.e. it's not actually reading the real SLI bandwidth numbers.

    In addition to using two connectors, SLI High Bandwidth uses a pixel clock of 650Mhz versus 400Mhz for normal SLI. Perhaps Pascal laptop cards running in SLI are using 650 MHZ pixel clocks and that's why it's called high bandwidth (however the bandwidth will still be half of what is available to desktop cards using two fingers.)

    Are the Pascal laptop SLI bridges constructed any differently than the Maxwell laptop SLI bridges? Perhaps your bridge is not capable of running at 650Mhz and thus limiting performance?

    However, from what I can tell, the SLI bridge bandwidth is only a function of the number of gpu's, the resolution, color depth, and framerate you are pushing. If you are running a 1080p screen at 60hz or 120hz, you should not be limited by a 400Mhz single SLI bridge. The way I've interpretted the information (and I'm probably wrong) is for 1080p at 60hz with 32bit color depth, the SLI bridge would have to be running at roughly 124Mhz.

    For 2160p at 60hz and 32bit color depth, the SLI bridge would have to be running at roughly 495Mhz

    I'm currently running two Maxwell mobile chips in SLI and they have no utilization issues pushing 3820*2160*32 at 60hz. That means, from what I can tell the SLI bridge used for Maxwell mobile cards is running at at least 500Mhz.

    Nvidia has something called LED SLI which runs at 540Mhz. Maybe this is what is used on Maxwell mobile cards.

    So assuming you're running at 1080p and 120hz you need to have a SLI bridge capable of running at ~250Mhz. The fermi era bridge should be capable of running at at least 400Mhz so I do not think this is your bottleneck (unless you are getting the utilization issues when pushing much higher framerates and resolutions).

    Or it could be that the cards (or software) are detecting that your cable is not capable of High Bandwidth SLI (i.e. 650 Mhz, 32 bit) and pre-emptively limiting the SLI bandwidth to ~half of what it should be?

    I'd be curious to hear what someone with more knowledge has to say on this. From what I can tell, the only reason you would need to have SLI High Bandwidth (specifically with a 32 bit bridge instead of a normal 16 bit bridge) would be for pushing insanely high framerates and resolutions like 4k at 120hz. Lower framerates and resolutions should not be affected and perhaps this is why the mobile Pascal cards only use 16 bit bridges? (But are they running at 650Mhz?)
     
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