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  1. #1
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    Question Above 4G decoding - floaty mouse

    My specs:
    i5 9600kf
    G.skill trident z 3200mhz cl 16, 2x8GB
    GeForce RTX™ 3070 VENTUS 3X OC - 8GB Vram
    ASUS Z390-i gaming
    RM650x

    I activated Above 4G decoding in BIOS, after I read it helped with performance. However: my mouse input lag improved when moving from place A to place B - like across a screen! But when doing small adjustments, mouse feels floaty and overall laggy.

    This option is meant for GPUs with more VRAM and for resizeable bar. I don't know exactly from how much GB you should turn this on. It is interesting option. But input lag is bad now!

    GPU is enabled in msi by default and I have it in pci-e gen3, I have on IOAPIC 24-119 entries.

    Any idea why Above 4G decoding cause weird lag?

  2. #2
    ROG Enthusiast Array howxcore PC Specs
    howxcore PC Specs
    MotherboardMaxims XI Hero- Wifi
    ProcessorCore I9 9900k 5.0 ghz
    Memory (part number)G.skill tridentz rgb 3600mhz 32gb
    Graphics Card #1rtx 3090 ftw3 ultra
    Sound CardSound Blaster X AE-5
    MonitorViewsonic XG270QG, BENQ PD3200U
    Storage #1970 evo m.2 1tb
    Storage #2Sandisk Ultra 3D SSD 2TB
    CPU Coolernzxt kraken x62
    Casenzxt 700i
    Power Supplyseasonic titanium 1000w
    Keyboard logitech g915 TKL
    Mouse logitech g502
    Headset Logitech G935 wireless
    Mouse Pad ICEMAT
    Headset/Speakers logitech z5500
    OS windows 10 pro 2004

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    Quote Originally Posted by empleat View Post
    My specs:
    i5 9600kf
    G.skill trident z 3200mhz cl 16, 2x8GB
    GeForce RTXâ„¢ 3070 VENTUS 3X OC - 8GB Vram
    ASUS Z390-i gaming
    RM650x

    I activated Above 4G decoding in BIOS, after I read it helped with performance. However: my mouse input lag improved when moving from place A to place B - like across a screen! But when doing small adjustments, mouse feels floaty and overall laggy.

    This option is meant for GPUs with more VRAM and for resizeable bar. I don't know exactly from how much GB you should turn this on. It is interesting option. But input lag is bad now!

    GPU is enabled in msi by default and I have it in pci-e gen3, I have on IOAPIC 24-119 entries.

    Any idea why Above 4G decoding cause weird lag?
    If you disable Above 4G decoding, does it go away?

  3. #3
    ROG Guru: White Belt Array
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    Quote Originally Posted by howxcore View Post
    If you disable Above 4G decoding, does it go away?
    Yep!

  4. #4
    ROG Enthusiast Array howxcore PC Specs
    howxcore PC Specs
    MotherboardMaxims XI Hero- Wifi
    ProcessorCore I9 9900k 5.0 ghz
    Memory (part number)G.skill tridentz rgb 3600mhz 32gb
    Graphics Card #1rtx 3090 ftw3 ultra
    Sound CardSound Blaster X AE-5
    MonitorViewsonic XG270QG, BENQ PD3200U
    Storage #1970 evo m.2 1tb
    Storage #2Sandisk Ultra 3D SSD 2TB
    CPU Coolernzxt kraken x62
    Casenzxt 700i
    Power Supplyseasonic titanium 1000w
    Keyboard logitech g915 TKL
    Mouse logitech g502
    Headset Logitech G935 wireless
    Mouse Pad ICEMAT
    Headset/Speakers logitech z5500
    OS windows 10 pro 2004

    Join Date
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    Quote Originally Posted by empleat View Post
    Yep!
    i'd just keep that off until a proper bios update that enables resize bar support officially

  5. #5
    ROG Guru: White Belt Array
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    Quote Originally Posted by howxcore View Post
    i'd just keep that off until a proper bios update that enables resize bar support officially
    I don't even have CPU which supports resizable bar, but it also should be enabled for GPUs with large VRAM. Mine 8GB. No idea, if I should enable it. It can be combination of things. I would like to know more, but didn't find much about it.

  6. #6
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    Quote Originally Posted by empleat View Post
    I don't even have CPU which supports resizable bar, but it also should be enabled for GPUs with large VRAM. Mine 8GB. No idea, if I should enable it. It can be combination of things. I would like to know more, but didn't find much about it.
    "Above 4G Decoding affects the amount of RAM allocated at a time for the processor to work with video memory. And this explains some increase in the consumption of RAM. Previously, you had to huddle in a 4GB block, while with the Above 4G, you can use the whole area.

    Resizable Bar allows the graphics API to pass large blocks of memory to the graphics card. Previously, they communicated in chunks of 256 megabytes, but now you can send a lot at once and from any part of the memory."

    Source: https://www.gameunion.tv/en/games/ab...ould-it-be-105

  7. #7
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    I have had it enabled with a 980 ti 8 GB with no issues. I don't notice any difference.

  8. #8
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    I've seen this happen!

    I have a PRIME-X470 PRO, and HARPOON RGB mouse connected to the USB-A port directly above the C port (CPU-connected). I've had the above 4G decode and rBAR options enabled since the first BIOS released with it. I did a Windows install earlier with both options disabled, and my cursor is smoother than ever. I currently have a RX 6600 XT. I've had a RTX 3060 and RX 580, but don't recall there being a difference on how the cursor felt. Basically, I assumed this was normal all this time.

    I've heard that if you touch either option, a hard CMOS reset may be needed to revert it. I believe this is true as I haven't noticed a cursor difference with past toggling of those options, and I've always done OS installs with the options enabled. This time I did the CMOS reset.

    With AMD GPUs, Above 4G Decode also affects the installation of the Pci Bus driver. With 4G decode disabled, that Bus driver doesn't get installed, and I notice my USB devices don't get nuked during the graphics driver install.

    I have a 2700X CPU also. SAM/rBAR show as supported from Radeon and NVIDIA control panels, and GPU-Z shows all Yes for rBAR stuff (except the driver support for the RX 580). I don't know if this is related to the CPU or changed at all by PCI-E 4.0 support.

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