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View Full Version : Above 4G decoding - floaty mouse



empleat
03-02-2021, 09:12 PM
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?

howxcore
03-03-2021, 04:06 PM
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?

If you disable Above 4G decoding, does it go away?

empleat
03-04-2021, 06:18 PM
If you disable Above 4G decoding, does it go away?
Yep!

howxcore
03-04-2021, 11:35 PM
Yep!

i'd just keep that off until a proper bios update that enables resize bar support officially

empleat
03-06-2021, 11:40 PM
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.

rascal_uk
04-16-2021, 10:59 AM
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/above-4g-decoding-your-bioss-dark-horse-what-it-and-should-it-be-105

cricketbones
04-19-2021, 05:03 PM
I have had it enabled with a 980 ti 8 GB with no issues. I don't notice any difference.

Espionage724
06-10-2022, 09:51 PM
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.