M4700 NVIDIA Quadro/Intel HD4000 Optimus issue solved?

Discussion in 'Dell Latitude, Vostro, and Precision' started by robs10, Sep 26, 2013.

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  1. robs10

    robs10 Notebook Evangelist

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    Did the issue of IGP/GPU Optimus switching ever get worked out? Most of what I read was to use the NVIDIA GPU, Optimus needed to be disabled in the BIOS to use the internal monitor, defeating the whole automatic graphics switching feature
    of Optimus and a bit of a PITA to use :-(.
     
  2. Aaron44126

    Aaron44126 Notebook Prophet

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    With Optimus enabled, the IGP will always drive the internal monitor. It doesn't switch the monitor over to the NVIDIA GPU... that's now how Optimus works.

    Optimus allows apps to be rendered by the NVIDIA GPU while the display is being driven by something else. The NVIDIA GPU can be used for rendering individual apps (sitting idle while it is not needed, saving power). It does the rendering internally and pipes the output to the IGP for compositing on the screen. As for which apps use the NVIDIA GPU and which ones use the Intel GPU, this is handled automatically by a database of definitions created by NVIDIA, but you can manually override any app you like in the NVIDIA control panel.
     
  3. robs10

    robs10 Notebook Evangelist

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    My understanding was that Optimus routes apps requiring less graphic muscle automatically go through the IGP to save power, but as soon as some threshold Optimus detects is reached, graphic intensive apps automatically route through the dedicated GPU (displaying on whichever display is being used). Do I have this wrong, and if so, is this pertain to just workstation type laptops?
     
  4. Aaron44126

    Aaron44126 Notebook Prophet

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    Yeah more or less correct. The key points are, while graphic intensive apps are routed through the discrete GPU, the display itself is always driven by the integrated GPU. Also, there isn't really a "threshold" that makes the NVIDIA GPU kick in. It's done on a per-app basis, using either settings you select or NVIDIA's default definitions to decide which app is driven by which GPU.

    Also, on the Precisions at least, the Intel GPU is only available on the internal display and the VGA port. Other displays (HDMI, DisplayPort, DVI on dock) will always be driven by the NVIDIA GPU, all of the time.
     
  5. tijo

    tijo Sacred Blame

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    Aaron is right, the display has to be driven by the IGP, think of it as a pass through when you use the nVidia GPU if you will, the IGP is not handling the calculations, but the signal has to pass through it. That is the reason why there is no optimus with the 10-bit IPS display, the IGP can't handle passing 10-bit per color to the display and as a result, it has to be bypassed entirely in order to be able to drive the display.
     
  6. robs10

    robs10 Notebook Evangelist

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    Let me see if I have it...running Internet Explorer, no is NVIDIA used, only Intel 4000...start AutoCAD and NVIDIA Quadro and Intel 4000 both run. Close AutoCAD and NVIDIA shuts down to save power....kind of like how a Quad core processor works. If Optimus is disabled in BIOS, NVIDIA GPU runs everything, even if only running Internet Explorer. If external monitor is used, NVIDIA Quadro runs all graphics, even if Optimus is enabled (guess they figure if you're running an external monitor, the Intel GPU may not have enough power for large HD displays, and you're plugging the laptop in and don't need to save battery power anyway)

    So the Optimus is only available on the 1366x768 screen, not on the 1920x1080...interesting...sorry to ask so many questions, but learning all this is cool!
     
  7. tijo

    tijo Sacred Blame

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    You have nothing to loose by asking, if you don't ask, you may never know and if you ask, you at least have the chance of getting an answer. ;)
    Pretty much, but as Aaron said, VGA can be driven by the Intel IGP. When you start Autocad, both run, but the IGP isn't handling the graphics so it's using very little power in that state. It would be possible to implement hardware switching where you'd have a separate controller that would switch between inputs from the IGP and GPU when needed, but that's not a very elegant solution. It's what was used in the past if I remember correclty and was phased in favor of software switching. The first implementation of switchable graphics required a reboot, the next one made the screen blank out for a second and then nVidia Optimus was born and later AMD's Enduro which allow for seamless switching.

    The M6700 still has extra hardware to allow completely disabling the IGP in the BIOS, but as far as I know, it's not involved in the graphics switching with optimus enabled.
     
  8. Aaron44126

    Aaron44126 Notebook Prophet

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    No, it works on the standard 1920x1080 as well. It only doesn't work on the IPS display (a 10-bit display that also runs at 1920x1080). The IPS display hasn't been available in the M4700 for a while so you're not likely to encounter one.
     
  9. tijo

    tijo Sacred Blame

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    Yup, Dell removed that option, any 8-bit per color panel will work with the IGP. The 1920x1080 Ultrasharp panel is a TN 8-bit display, so no problem there. The PremierColor (the 10-bit RGB LED IPS) was removed so like Aaron said, you're unlikely to encounter it unless you go for a refurb.

    It can get pretty complicated, you have various technologies for displays like TN, IPS, PLS, etc.; the number of bits per color (6, 8, 10, etc.), gamut, different types of backlighting and those various specs can be "mixed and matched" by the display manufacturers to an extent. Therefore, it can get pretty complicated to get the full specs for a particular display. The takeaway is that for the Mx700 series, you have two main types, TN and 8-bit (lower resolutions and Ultrasharp option) and IPS + 10-bit (PremierColor option).
     
  10. robs10

    robs10 Notebook Evangelist

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    Thanks Tijo...thought the Ultrasharp displays were always IPS based on the external display series. Do you know if the 1080 Ultrasharp diaplays in the M4700 the same as the FHD 1080 displays in the Latitudes?
     
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