NVIDIA Resizable Bar (rBAR) - are you enabling it right?

[LucShep]

Just posting some stuff that is not DCS specific but still worth sharing (or so I hope).

Before anything, and for those willing to go ahead and try this for themselves, I'll assume you already know what Is Resizable BAR on a GPU, and also that you have it already enabled, in your motherboard BIOS and in your NVIDIA 30 or 40 series graphics card.
If you don't know if Resizable Bar (rBAR) is enabled, nor how to enable it, then I suggest to search for guides on that, there's plenty around for this delicate process.
Here's one among many others: youtube.com/watch?v=FUO_8bykkc4

So, I've been using Resizable BAR (rBAR) for a long time now, but never felt too sure that it's making a real difference with games.
That was until recently, when I found out that, for NVIDIA 30 and 40 series GPUs, for it to work it should be "forced". And better if with aproppriate settings.
After that, I find there's a noticeable difference with plenty games, some run impressively smoother now (Ghost of Tsushima, for example).

To force and adjust rBAR settings, you'll need a third party app, called Nvidia Profile Inspector:  https://github.com/Orbmu2k/nvidiaProfileInspector

For those unfamiliar with this fantastic app, it opens access to more Nvidia driver settings than those found in the Nvidia Control Panel.
With it, we can adjust a lot of settings, individually (per game title) or globally (for all profiles), as prefered.

So, opening Nvidia Profile Inspector...

• If you wish to adjust settings of the Global profile (so, for all game profiles) click the "house icon" (represents "Home" or "Main profile").
  Its settings will then be listed.
   
• If you wish to adjust settings individually for one game title only, then search for it in the "Profiles" (top left).
  You can manually scroll to locate the game title of your choice. 
  Or you can use the search box and type the game title name to be located - example: for DCS, type"Digital Combat Simulator" (without comas).

Once with the profile of your choice open, scroll down through the settings, to the "Common" section.
There you'll find the three rBAR settings.

These are the rBAR settings that, so far, I found best for my own GPU and games:

rBAR feature  - - - - - -   Enabled

rBAR options  - - - - - -  0x00000001

rBAR size limit  - - - - -  0x0000000100000000 

On this last "rBAR size limit" setting, some important notes. These are the limits available:

• 0x000000000C800000 = 200MB VRAM
• 0x0000000012C00000 = 300MB VRAM
• 0x0000000040000000 = 1GB VRAM 
• 0x0000000060000000 = 1.5GB VRAM (default Nvidia value for most games?)
• 0x0000000080000000 = 2GB VRAM
• 0x0000000100000000 = 4GB VRAM
• 0x0000000200000000 = 8GB VRAM
• 0x0000000280000000 = 10GB VRAM

It seems NVIDIA goes with 1.5GB for most game titles(?).
Theoretically, only the last 4 requests of 256MB are said to be remembered. So, theoretically, more than 1GB for games is unnecessary. 

The 1GB limit is also the highest recommended value for GPUs with smaller amounts of VRAM (8GB or less) because, more than that, there is a very strong chance that VRAM overflow will happen, making things worse (the GPU may have to erase the VRAM, any benefits are lost).

But there are game titles that can benefit if you set a larger rBAR size limit, if you have available VRAM.

I have set the rBAR size limit to 4GB, as that seems plenty and I have a GPU with a lot of VRAM (using an RTX 3090 24GB).

Of course, YMMV. Feel free to play with different rBAR settings.
 

Edited June 2, 2024 by LucShep

[diego999]

From what I read in an old discussion, rBAR needs to be coded into the game itself to be able to function. Forcing it will make no difference.

Doesn't hurt to try tho. Will test tonight and report if there's any improvements. 

[corbu1]

rBAR  needs to be coded in the individual game or sim is as I understood it as well. I don’t think it’s coded into DCS and I never realized a benefit in DCS.

[Sn8ke]

Has it been confirmed resizable bar works in DCS?

[LucShep]

On 2/13/2025 at 11:30 PM, Sn8ke said:

Has it been confirmed resizable bar works in DCS?

It hasn't been confirmed that RBAR works for DCS (not implemented by ED, is my guess) and I honestly never noticed a difference with it either on or off.

I do use it for most other games and it does make a really noticeable difference with some.

 

Edited February 19 by LucShep