Hi all,

I did a reinstall of my Windows and sim. But ran still run into VRAM issues on big airports like eham and egll always in the yellow or red on medium settings. Now I remember that turning rebar off in the BIOS helps. So I did that again, and boom, VRAM issues fixed. It just gives me more than 1 GB of vram extra and overall less stutter. Still unsure why this happens, and Asobo doesn't address this or give this advice when having issues. My system 7800x3d, 64gb ram and an 9070xt 16gb. Hope others try it again. For me it does wonders.

Difficult decision. It might yield negative results for other titles.

Gemini "says":

Turning off Re-size BAR (Resizable BAR) in your BIOS essentially changes how your CPU and GPU talk to each other. On a Windows 11 desktop, disabling this feature can have a noticeable impact on gaming performance, though it won't "break" your computer.

Here is the breakdown of what is actually happening under the hood:

The Technical Definition

Normally, a CPU can only access your graphics card’s memory (VRAM) in small 256 MB chunks. This is a legacy limitation from the 32-bit era. Even if you have a high-end card with 16 GB of VRAM, the CPU has to "queue up" and move data through a tiny window.

When you turn Re-size BAR off, you are forcing the system back into this restricted communication mode.

What Happens When It's Off?

• Reduced Frame Rates: In modern games (like Cyberpunk 2077, Forza Horizon 5, or Starfield), you will likely see a 5% to 15% drop in FPS. The GPU has to wait longer for the CPU to send it the textures and shaders it needs.

• Increased Bottlenecking: In CPU-heavy scenarios, your processor becomes less efficient at feeding the graphics card, leading to "stutter" or inconsistent frame times.

• Legacy Stability: The only real reason to keep it off is if you are playing very old games (pre-2014) that occasionally glitch when the feature is enabled, though this is rare nowadays.

Why You Usually Want It ON

For Windows 11 users with modern hardware (NVIDIA RTX 30-series or newer, or AMD Radeon RX 6000-series or newer), Re-size BAR is considered a "free" performance upgrade.

---

How to Check if It’s Actually Off

You don't necessarily have to go back into the BIOS to see the status. You can check directly in Windows 11:

1. Open the NVIDIA Control Panel (or AMD Software).

2. Click System Information in the bottom left corner.

3. Look for Resizable BAR in the list. It will say "Yes" or "No."

Summary: Unless you are troubleshooting a specific, weird technical glitch in an old application, you generally want to keep this setting Enabled to get the full speed out of your hardware.

6 minutes ago, jcomm said:

Gemini "says":

Turning off Re-size BAR (Resizable BAR) in your BIOS essentially changes how your CPU and GPU talk to each other. On a Windows 11 desktop, disabling this feature can have a noticeable impact on gaming performance, though it won't "break" your computer.

Here is the breakdown of what is actually happening under the hood:

The Technical Definition

Normally, a CPU can only access your graphics card’s memory (VRAM) in small 256 MB chunks. This is a legacy limitation from the 32-bit era. Even if you have a high-end card with 16 GB of VRAM, the CPU has to "queue up" and move data through a tiny window.

When you turn Re-size BAR off, you are forcing the system back into this restricted communication mode.

What Happens When It's Off?

• Reduced Frame Rates: In modern games (like Cyberpunk 2077, Forza Horizon 5, or Starfield), you will likely see a 5% to 15% drop in FPS. The GPU has to wait longer for the CPU to send it the textures and shaders it needs.

• Increased Bottlenecking: In CPU-heavy scenarios, your processor becomes less efficient at feeding the graphics card, leading to "stutter" or inconsistent frame times.

• Legacy Stability: The only real reason to keep it off is if you are playing very old games (pre-2014) that occasionally glitch when the feature is enabled, though this is rare nowadays.

Why You Usually Want It ON

For Windows 11 users with modern hardware (NVIDIA RTX 30-series or newer, or AMD Radeon RX 6000-series or newer), Re-size BAR is considered a "free" performance upgrade.

---

How to Check if It’s Actually Off

You don't necessarily have to go back into the BIOS to see the status. You can check directly in Windows 11:

1. Open the NVIDIA Control Panel (or AMD Software).

2. Click System Information in the bottom left corner.

3. Look for Resizable BAR in the list. It will say "Yes" or "No."

Summary: Unless you are troubleshooting a specific, weird technical glitch in an old application, you generally want to keep this setting Enabled to get the full speed out of your hardware.

There is a big thread about rebar and VRAM improvements. So Gemini is wrong and just gives very general information about the function. Yes it should. But it doesn't as tons of people saw big improvent. If you are having VRAM issues it's an good option to try. About other games yes that is a doen side but it the improvements % are not that big anyway 

Well,

just checked in my RTX 3060 Ti and it's set to "No"  😁

My 4090 with the 9800X3D actually runs BETTER with rBAR on. So you have to test this on your very specific hardware combo, seems this is not a simple yes or no for everybody...

Tried both on and off.  Off did improve my VRAM usage a little but after a fair bit of testing, I got better performance with it switched back on.  If you have low VRAM isues, you may be better having it off or keep it on and reduce your othr msfs or Nvidia settings.

Everyones systems and preferences are going to be different on this.

Thanks, OP. I only have 12 GB Vram. I had been using Rebar on. Turning it off today allowed me to turn the msfs graphic settings up higher.

I had them up this high with Rebar on for weeks, but yesterday I landed at default MS O'hare (KORD). What a resource hog airport! That airport is large! I no longer have to turn graphics lower to land at O'Hare with rebar off.

I jumped on the resize bar train and also was silly and changed other settings at the same time. A few weeks went by and I remembered I enabled it — I turned it off and it was a brand new sim. My VRAM went from 96% usage down to the low 70’s. Mind you, I’m on windows 10, with an i7-11700k, 3080 and 32gb of ram.

I'm also running with Rebar OFF.

Despite having a high-end system (9800X3D, 64 GB, 5070 Ti 16GB), I feel zero tangible difference in performance (didn't run precise benchmark neither). Keeping it disabled actually simplifies things for me. It gets rid of the nagware/messages while I'm running mostly all in Ultra settings and using MSFS_AutoFPS to manage my LODs and other stuff it's good at.

Edited May 6May 6 by vbazillio

Re-Bar on here. 

I get far smoother FPS and an decrease in both GPU and main thread timing when I have re-bar ON. Thats with a 5090 where VRAM isn't an issue.

RTX 5080 here and rebar off through nvidia inspector, in this way I can set it off just for MSFS24. With rebar on I have problem with vram because my  graphics are almost all ultra, ray tracing and, DLSS, tdfi md11, complex airports, etc.

So....err..... how do you set it off/on in the BIOS?

We have every conceivable piece of information about it in this thread, other than that 😄

I appreciate it may be known to most... but not all.

Thanks!

33 minutes ago, Claudius_ said:

RTX 5080 here and rebar off through nvidia inspector, in this way I can set it off just for MSFS24. With rebar on I have problem with vram because my  graphics are almost all ultra, ray tracing and, DLSS, tdfi md11, complex airports, etc.

Same here, with a 4080 (16GB VRAM), I see better overall performance (and better overall "experience") with RBAR OFF via NVI for MSFS compared to the negligible FPS improvement at a heavy VRAM tax with it ON.  

Edited May 6May 6 by McLaren

you have an nvidia card so it should be possible to disable it in the nvidia software @JYW

Edited May 6May 6 by funkyj4ever