Tuesday, January 12th 2021

NVIDIA Details its Resizable-BAR Feature Rollout, Eligible Products

NVIDIA on Tuesday announced a roll-out of its implementation of the PCI-SIG resizable base-address register (BAR) feature to select GeForce products. The feature enables your CPU to see the entire video memory of your graphics card as one addressable block, rather than through 256 MB apertures. This should improve certain kinds of 3D rendering workloads, and game engines that are optimized to use it should see a tangible performance boost. AMD earlier introduced the exact same feature under its marketing name "Smart Access Memory," with its Radeon RX 6000 series.

NVIDIA announced that resizable-BAR support will be made available to GeForce RTX 30-series "Ampere" desktop graphics cards, notebooks that have RTX 30-series "Ampere" mobile GPUs, and future products. The support requires not just a compatible graphics card, but also a motherboard that supports the feature. Most leading motherboard- and OEM desktop manufacturers began rolling out resizable-BAR support through UEFI firmware updates. Using the feature requires you to run your machine in native UEFI mode (with CSM disabled).
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52 Comments on NVIDIA Details its Resizable-BAR Feature Rollout, Eligible Products

#1
evernessince
Will be interesting to see if this offers the same performance uplift that AMD is seeing.
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#2
Khonjel
Expected but sad that everyone (AMD, Nvidia) forgot us last gen buyers. Would've loved a small performance increase on my RTX 2060.
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#3
wolf
Performance Enthusiast
Looks like my X570 board has a BIOS with Resize BAR now, looking forward to seeing if there are any gains to be had with my 3080 when the time comes.
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#4
RJARRRPCGP
MSI reports the new beta BIOS for the B450 Tomahawk having resize-BAR.
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#5
Mussels
Moderprator
Great that we need BIOS updates to fix this, means that all the manufs are going to have to step up their games
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#6
Max(IT)
So much for a feature supposedly requiring a Zen 3 CPU...
I'm going to enjoy it on a 3900X without paying AMD the ridiculous price they are asking for a Zen 3 CPU (and without using a poor RT performance RX 6800 card).
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#7
Mussels
Moderprator
Max(IT)
So much for a feature supposedly requiring a Zen 3 CPU...
I'm going to enjoy it on a 3900X without paying AMD the ridiculous price they are asking for a Zen 3 CPU (and without using a poor RT performance RX 6800 card).
it never required zen 3, it's just that *at launch* zen 3 and big navi were the only supported combinations.

It was never limited to just that hardware, that was just the starting point.
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#8
thesmokingman
Mussels
it never required zen 3, it's just that *at launch* zen 3 and big navi were the only supported combinations.

It was never limited to just that hardware, that was just the starting point.
It sure made for good clickbait though.
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#9
daehxxiD
Pretty disappointing that the RTX 20-series won't get the feature. I'd assume especially a GPU like my 2060 with only 6GB Ram could really benefit from this.
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#10
Mussels
Moderprator
daehxxiD
Pretty disappointing that the RTX 20-series won't get the feature. I'd assume especially a GPU like my 2060 with only 6GB Ram could really benefit from this.
at this stage we dont know if GPU's with more or less VRAM benefit.

As someone with 64GB system ram and a 24GB GPU, i'm hoping its on the 'more' side
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#11
daehxxiD
Mussels
at this stage we dont know if GPU's with more or less VRAM benefit.

As someone with 64GB system ram and a 24GB GPU, i'm hoping its on the 'more' side
Definitely a topic I would like to see explored. Also, next GPU I'm getting is gonna be one with lots of VRAM. I feel like the RTX 2060 is really held back by its small framebuffer, especially when enabling RTX. Had issues with texture resolution in both, Control and CP2077 (both times having to reduce Texture Res to Medium) even though I only game at 1080p + DLSS.

If we are moving towards streaming Textures straight from SSD to VRAM, having faster access to the VRAM should definitely help. Not sure if the streaming in game engines has to pass through CPU tho, but that would explain why we are seeing massive leaps in performance when tested on AC: Valhalla with Resize-BAR enabled for example.
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#12
stimpy88
So they won't lift the artificial limit on the RTX20xx series, or the last gen GTX series? I hate nGreedia.
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#13
Max(IT)
Mussels
it never required zen 3, it's just that *at launch* zen 3 and big navi were the only supported combinations.

It was never limited to just that hardware, that was just the starting point.
you know better than me that AMD wanted customers to believe that... otherwise they would have added Zen 2 support from the beginning.
There were also "rumors" pointed at hardware lack of support for Zen 2, at the beginning... it was just marketing.
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#14
Mussels
Moderprator
stimpy88
So they won't lift the artificial limit on the RTX20xx series, or the last gen GTX series? I hate nGreedia.
you think they could really release BIOS updates for every single 20 series GPU out there? the work would be massive, for very little gain.
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#15
1d10t
Would like to see which side gain the most from this R-BAR. Funny, I read in somewhere (VCN I suppose), that Intel will also enable R-BAR but didn't mention any Radeon card. Grumpy old granpa :D
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#16
daehxxiD
Mussels
you think they could really release BIOS updates for every single 20 series GPU out there? the work would be massive, for very little gain.
It depends. Remains to be seen how much of this Resize-BAR stuff is just hype or could be exploited for massive performance gains. With the consoles all sporting SSDs and a unified memory architecture, I certainly could see game engines leveraging the fast access to (V)RAM directly with the CPU. The example I posted before, about asset streaming, seems to be a big part of UE 5 for example.

Although of course, BIOS updates for GPUs are not really a common thing to do. A lot of things could go wrong for what is, at the moment at least, not much gain to be had.

What I don't get is that apparently Linux has had this feature for a while now. Does that mean that on linux resize-BAR works without any BIOS updates or was it just there as in, available in the kernel?
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#17
_UV_
stimpy88
So they won't lift the artificial limit on the RTX20xx series, or the last gen GTX series? I hate nGreedia.
How about AMD enable this for RX 5700/5600/580/480/Vega/Radeon VII? Wait, its just for "latest" generation...
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#18
obsidian24776
At least Nvidia has been quick to implement this feature, how many years did it take for them to implement FreeSync ... Sorry GSync Compatability.
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#19
dampflokfreund
daehxxiD
Definitely a topic I would like to see explored. Also, next GPU I'm getting is gonna be one with lots of VRAM. I feel like the RTX 2060 is really held back by its small framebuffer, especially when enabling RTX. Had issues with texture resolution in both, Control and CP2077 (both times having to reduce Texture Res to Medium) even though I only game at 1080p + DLSS.

If we are moving towards streaming Textures straight from SSD to VRAM, having faster access to the VRAM should definitely help. Not sure if the streaming in game engines has to pass through CPU tho, but that would explain why we are seeing massive leaps in performance when tested on AC: Valhalla with Resize-BAR enabled for example.
Had zero issues in Control, always max textures and at 1440p+DLSS and RTX on my 2060. There can be a bug where picture textures may get blurry, just turn textures to high and then back to max and that fixes it. It's not a VRAM issue at all but a streaming issue from the engine, cards with more VRAM suffer as well. VRAM allocation is not close to being maxed out.

Cyberpunk has a memory leak issue where performance gets gradually worse, but the more VRAM you have or the lower your settings are, the more time it takes for it to take effect. It will happen on any 8 and 6 GB card though, at some time. That is why many people experienced better performance after restarting the game (which lead to that memorypool.ini placebo)
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#20
Grings
Has anyone run comparisons of this feature yet when limited to pci-e 3.0?
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#21
thesmokingman
Max(IT)
you know better than me that AMD wanted customers to believe that... otherwise they would have added Zen 2 support from the beginning.
There were also "rumors" pointed at hardware lack of support for Zen 2, at the beginning... it was just marketing.
The rumors were from AMD? Oh wait AMD is the bad. You wouldn't even freaking know about resizeable bar if it weren't for AMD... facepalm.
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#22
daehxxiD
dampflokfreund
Had zero issues in Control, always max textures and at 1440p+DLSS and RTX on my 2060. There can be a bug where picture textures may get blurry, just turn textures to high and then back to max and that fixes it. It's not a VRAM issue at all but a streaming issue from the engine, cards with more VRAM suffer as well. VRAM allocation is not close to being maxed out.

Cyberpunk has a memory leak issue where performance gets gradually worse, but the more VRAM you have or the lower your settings are, the more time it takes for it to take effect. It will happen on any 8 and 6 GB card though, at some time. That is why many people experienced better performance after restarting the game (which lead to that memorypool.ini placebo)
Hmm... I never had any Textures not loading when reducing the Texture Detail to Medium in Control (I think, I just know I didn't max it), whereas it was happening regularly while traversing the world at High/Ultra. (Also, VRAM utilization was always around 5.5gig, no matter what texture setting).

For Cyberpunk: Yeah, I am aware that there is a "memory leak", as it almost halves my framerate after some time. However, it is also much less likely to occur if I lower texture resolution to Medium. Indeed, I think what that "memory leak" really is, is the RED Engine using system memory as "extended" video memory to prevent crashing. Unfortunately this means that the game sometimes needs to fetch data from that slow pool of memory, which slows performance considerably! There is definitely points in the game, where the engine genuinely runs out of memory if I max out settings with Textures on High. It's easiest to reproduce when you go to the market close to where the fixer "Regina" is holed up. It generally starts hitching while running through that market and it becomes really obvious, when you switch to photomode. In that case I have my VRAM utilization pegged at 6144 (or thereabout) and besides the constant hitching you'll have NPCs disappearing and reappearing or actually parts of your own charmodel (clothes/hair etc.) disappearing and reappearing.

So yeah, VRAM limitations are a real thing, especially if you use RTX which needs a good chunk of extra memory.
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#23
Mussels
Moderprator
daehxxiD
Hmm... I never had any Textures not loading when reducing the Texture Detail to Medium in Control (I think, I just know I didn't max it), whereas it was happening regularly while traversing the world at High/Ultra. (Also, VRAM utilization was always around 5.5gig, no matter what texture setting).

For Cyberpunk: Yeah, I am aware that there is a "memory leak", as it almost halves my framerate after some time. However, it is also much less likely to occur if I lower texture resolution to Medium. Indeed, I think what that "memory leak" really is, is the RED Engine using system memory as "extended" video memory to prevent crashing. Unfortunately this means that the game sometimes needs to fetch data from that slow pool of memory, which slows performance considerably! There is definitely points in the game, where the engine genuinely runs out of memory if I max out settings with Textures on High. It's easiest to reproduce when you go to the market close to where the fixer "Regina" is holed up. It generally starts hitching while running through that market and it becomes really obvious, when you switch to photomode. In that case I have my VRAM utilization pegged at 6144 (or thereabout) and besides the constant hitching you'll have NPCs disappearing and reappearing or actually parts of your own charmodel (clothes/hair etc.) disappearing and reappearing.

So yeah, VRAM limitations are a real thing, especially if you use RTX which needs a good chunk of extra memory.
I looked at your system specs and i'm concerned as to how 2x8 = 26
Also, the GTX 970 has 3.5GB VRAM and may be your problem, even at 768p
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#24
Arctucas
Mussels
you think they could really release BIOS updates for every single 20 series GPU out there? the work would be massive, for very little gain.
It was on January 22, 2008 when the capacity was proposed Resizable BAR, which would be admitted on April 24, 2008. This technology is integrated within the PCI Express 3.0 standard.

Would it not be the GPU manufacturer to do the BIOS update?

Some would do it, maybe others would not.

Same goes for motherboards. Intel platforms since Haswell can do it.

nVIDIA is, once again, trying to sell product by making older products less attractive. And, who can actually find a 3080 or 3090?
daehxxiD
<SNIP>

Although of course, BIOS updates for GPUs are not really a common thing to do. A lot of things could go wrong for what is, at the moment at least, not much gain to be had.

<SNIP>
Installing eVGA Precision X1 with a eVGA RTX GPU will automatically check and offer to update the firmware. Have not read that anyone has had a bricked GPU because of it.
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#25
Mussels
Moderprator
Nvidia would have to release it for all the GPU types
then the manufs would have to do it

And they would simply not do it for discontinued products - look at all the fluff for backdating ryzen CPU support, the companies basically said to get F'd unless they were still selling them (such as B450 being supported when x370 was not)
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