Nvidia GPU owners may be losing performance because of a simple setting that's disabled by default — enabling Resizable Bar with Profile Inspector can enhance GPU performance by up to 10% in 3DMark
Some applications still benefit from manually enabling ReBAR.
YouTuber JayzTwoCents discovered that manually enabling Resizable Bar in certain non-whitelisted games/applications can yield a noteworthy performance boost. The YouTuber published a video showcasing an impressive 10% improvement in score in 3DMark Port Royal from simply turning ReBAR on with Nvidia Profile Inspector.
JayzTwoCents discovered this feature as he was diagnosing some performance issues with his extreme overclocking rig, featuring a Core i9-14900KS and RTX 5090, aimed at competing against LTT labs and extreme overclocker Splave (who has also written content for us). The Intel-powered rig was underperforming in 3DMark Port Royal by several thousand points compared to his GPU test rig featuring a Ryzen 7 9800X3D.
After talking with Splave, the YouTuber allegedly discovered that most (if not all) extreme overclockers (using Intel-based CPUs) are manually activating Resizable Bar with Nvidia Profile Inspector for 3DMark. Simply turning on ReBAR (in the driver) gave JayzTwoCents' 14900KS rig a 3,304-point boost, starting at 37,105 points and moving up to 40,409 points.
Resizable Bar became mainstream in 2020 when AMD began supporting the feature with its Ryzen 5000 CPUs and RX 6000 series GPUs, calling it Smart Access Memory (SAM). The technology debuted with PCIe 2.0 all the way back in 2006, but it wasn't until 2020 that CPU and GPU manufacturers realized its benefits, particularly for gaming. ReBAR changes the amount of data that can be transferred in one "trip" from the GPU to the CPU, which is usually constrained to a 256MB "aperture". ReBAR removes this limitation altogether.
Despite its benefits, Resizable Bar also has its quirks. It does not benefit every game, and some games don't benefit at all from turning ReBAR on. Worse still, some games drop performance with ReBAR enabled. This has forced GPU manufacturers such as Nvidia to test ReBAR on a game-by-game basis and only enable it by default in their GPU drivers if a game responds well to the feature.
Still, enthusiasts have found over the past several years that Nvidia has not whitelisted all games or applications that benefit from ReBAR enablement. Manually testing ReBAR enablement in games that Nvidia has not yet whitelisted can yield significant performance improvements. This is usually done with Nvidia Profile Inspector, which is an application that provides complete control over Nvidia's drivers, bringing to light features not visible in the Nvidia Control Panel. ReBAR can be forced on globally (in the driver) or on a per-application/game basis with Profile Inspector.
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Aaron Klotz is a contributing writer for Tom’s Hardware, covering news related to computer hardware such as CPUs, and graphics cards.
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aberkae Reply
Community should make a white list check list for both AMD and Intel platforms. From the comments on that video it seems that it can be disabled for for AMD and Intel. Nvidia is hyperfocused on ai. Gaming is an afterthought.BTM18 said:Its left off by default for a reason.
FAFO -
YSCCC But actually it depends on what game and GPU you have.Reply
Right now due to MSFS 2024 with some nicer addon, even at 1080p the game will instantly load up to 13-14Gb of VRam, once Rebar is enabled it instantly gets stutter hell, I have a 9070XT for 1080p and it goes like 50fps for high quality addon and airport, with re bar... 15-25fps.. -
ZGUY85 Article doesn't mention that a man named Allen or "Splave" who owns an SI company discovered this and not Jay, which Jay himself gives credit to in his video.Reply -
rambo919 Reply
So the ACTUAL reason for rebar is optimizing games for high VRAM GPU's? Why does no one just say that?YSCCC said:But actually it depends on what game and GPU you have.
Right now due to MSFS 2024 with some nicer addon, even at 1080p the game will instantly load up to 13-14Gb of VRam, once Rebar is enabled it instantly gets stutter hell, I have a 9070XT for 1080p and it goes like 50fps for high quality addon and airport, with re bar... 15-25fps..
EDIT: this actually might be a good explanation for recent reviewer benchmark problems regarding VRAM.... maybe the problem games on low VRAM GPU's are because rebar is enabled? -
Alvar "Miles" Udell Woo, 3DMark, that's such a great game! And the results have been repeated and confirmed by TomsHardware so this doesn't appear to just be a paid publicity piece for someone on Youtube!Reply
Oh wait, it's not. And oh, it hasn't... -
YSCCC Reply
No, enabling Re-bar, given the game use considerably less VRam than the GPU have, you can have the CPU utilizing the much faster VRam than the slow DDR4/5, so add some 10% performance, but when the game itself uses so much VRam, the Rebar having the CPU occupying the Vram will starve the GPU, and created the stutter hell...rambo919 said:So the ACTUAL reason for rebar is optimizing games for high VRAM GPU's? Why does no one just say that?
EDIT: this actually might be a good explanation for recent reviewer benchmark problems regarding VRAM.... maybe the problem games on low VRAM GPU's are because rebar is enabled?
Sadly for Flight simming, the base game is running lightening fast with Rebar, but those high realism aircraft, very detailed airport modelling including some random guys moving around the airport will eat up so much Vram by default, Rebar is only usable in 1440p with 24GB+ cards -
rambo919 Reply
I practice that just gets confusing....YSCCC said:No, enabling Re-bar, given the game use considerably less VRam than the GPU have, you can have the CPU utilizing the much faster VRam than the slow DDR4/5, so add some 10% performance, but when the game itself uses so much VRam, the Rebar having the CPU occupying the Vram will starve the GPU, and created the stutter hell...
Sadly for Flight simming, the base game is running lightening fast with Rebar, but those high realism aircraft, very detailed airport modelling including some random guys moving around the airport will eat up so much Vram by default, Rebar is only usable in 1440p with 24GB+ cards