Nvidia begins rolling out Resizable BAR support for RTX 3000 GPUs

mongeese

Posts: 483   +109
Staff member
Highly anticipated: Nvidia has finally begun rolling out Resizable BAR support, beginning with the desktop RTX 3060 and a select few RTX 3000-series equipped laptops. Enabling it can be a bit of a hassle, but it’s a free upgrade, so it gets a thumbs up.

Resizable BAR is a feature of the PCIe standard that enables a system’s CPU to see the entirety of the GPU’s memory subsystem, instead of just a small 256 MB portion. Implementing the feature requires low-level support in the CPU, motherboard, and GPU, which is how AMD, who designs all three, was the first to market with a Resizable BAR implementation called SAM (smart access memory).

In our testing, enabling SAM on an RX 6800 could improve a game’s average frame rate by up to 20%, or harm it by up to 10%. In most titles, though, enabling the feature did almost nothing, which is reflected by the average improvement: just 3%.

Understandably, then, Nvidia is taking a different route. Their drivers will leave the Resizable BAR disabled by default, and only switch it on in titles where Nvidia’s found that it improves performance. As of writing, that’s eight titles:

  • Assassin’s Creed Valhalla
  • Battlefield V
  • Borderlands 3
  • Forza Horizon 4
  • Gears 5
  • Metro Exodus
  • Red Dead Redemption 2
  • Watch Dogs: Legion

In these games, Nvidia says, Resizable BAR can improve performance "from a few percent, up to 10%." In late March, when the rest of the RTX 3000-series receives support for Resizable BAR, more games will be added to the list. Nvidia’s selective approach is undoubtedly a good idea (if done right) but unfortunately, it’s an advantage that’s negated by the complexity of enabling the Resizable BAR.

In laptops, the situation is okay but not great: some laptops will come with the Resizable BAR enabled, some won’t, and there’s nothing you can do about it. Nvidia says to "check with each laptop manufacturer to discover if Resizable BAR is supported on a particular model."

Desktop compatibility is a game of 3D chess. Enabling Resizable BAR, or, equally likely, discovering that your system doesn’t support it, is a five-step process. First, you’ll need to check if your CPU is compatible: all AMD 5000-series CPUs are, as are all 10th-gen Intel processors, but only the i5, i7, and i9 series from the upcoming 11th-gen will have compatibility. Simple enough...

Step two: check your motherboard’s chipset. AMD 500-series chipsets are compatible (if undesirable, at the moment) and the 400-series chipsets are compatible on motherboards that are also compatible with Ryzen 5000-series CPUs. The 500-series chipsets Intel’s announced as of writing are all compatible, and so are all their 400-series chipsets. Still with me?

Step three is more troublesome: you’ll need to update your motherboard’s SBIOS, but you'll just have to hope that an update exists. According to Nvidia, "the following manufacturers are offering SBIOS updates for select motherboards to enable Resizable BAR with GeForce RTX 30 series desktop graphics cards: Asus, Asrock, Colorful, EVGA, Gigabyte, and MSI."

Fourth, you’ll need to update your GPU’s VBIOS, unless you’re one of the lucky few with a new RTX 3060. For Founder’s Edition owners, Nvidia will provide the update themselves, but everyone else will need to download the update from their GPU manufacturer’s page.

And the home stretch: update your GPU drivers. Afterward, you can check if the Resizable BAR is working correctly in the Nvidia Control Panel, inside the System Information tab.

Permalink to story.

 

VitalyT

Posts: 5,487   +5,077
I would like to add that something is fundamentally wrong with nVidia's 3000 card design, especially 3090. The fact that Alienware has been selling its 3090 rigs with the card half the size of the original is a testament to that. There was never any real need to produce such a monstrosity, it's just lazy-a$$ engineering on nVidia's part, that's all.

 
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Peter Farkas

Posts: 532   +378
I am keen to see which exact motherboards will get the new BIOS from the manufacturers. I have a feeling my Asrock B460M Steel Legend will not be among those.
RBAR isn't really a game changer but if BIOS and driver support is ok and stable it may be worth the little extra performance.
 

Tom Yum

Posts: 85   +205
So AMD is trying to make people upgrade their cpu when there is no real need to do so.
Not really, there are changes to Zen3 that allowed for the faster translation of memory addresses between address spaces (PDEP instructions went from 3 to 1 cycle) that made resizable BAR actually improve performance. Intel has supported the same instructions and performance since Haswell (but for some reason never supported resizable BAR). All nVidia are doing is updating their drivers and bios (though why that would be needed is less clear)to use those PDEP instructions, but without CPU support resizable BAR wouldn't offer any performance increase.

If anyone should be looked at sceptically it should be nvidia, as they are only updating drivers there is no reason it should be limited to 3000 series. 1000 and 2000 series should also benefit from resizable BAR, as it doesn't require any particular GPU hardware to support. At least with AMD, there was a hardware reason by pre Zen3 didn't have (as their slower PDEP instructions made it not worth supporting).
 
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QuantumPhysics

Posts: 4,708   +5,110
I would like to add that something is fundamentally wrong with nVidia's 3000 card design, especially 3090. The fact that Alienware has been selling its 3090 rigs with the card half the size of the original is a testament to that. There was never any real need to produce such a monstrosity, it's just lazy-a$$ engineering on nVidia's part, that's all.



NVIDIA built the 3090 to be huge and take up 3 whole slots. Just 2 fans.

My 3090 FTW3 takes up 2.5 slots and has a 3rd fan.

An AIO card (Kingpin) takes up just 2 slots.

I would trade my FTW3 for a KINGPIN if I can
 

NeoMorpheus

Posts: 402   +765
I am honestly surprised that nvidia didnt do one of their characteristics maneuvers and somehow made this locked to their cards only.

I know, its an open standard, motherboard side, but still, they are the masters of the lock-in technique and they know that their loyal followers love anything that locks them to nvidia hardware.

Perhaps with time, they will convince motherboards manufacturers to include some stupid nvidia chip, call it g-BAR and watch the fanbois foam.
 

nnguy2

Posts: 266   +517
I am honestly surprised that nvidia didnt do one of their characteristics maneuvers and somehow made this locked to their cards only.

I know, its an open standard, motherboard side, but still, they are the masters of the lock-in technique and they know that their loyal followers love anything that locks them to nvidia hardware.

Perhaps with time, they will convince motherboards manufacturers to include some stupid nvidia chip, call it g-BAR and watch the fanbois foam.

Resizabke Nbar... Now give nvidia all your monies
 

Gregtombstone

Posts: 16   +12
Frankly I think Techspot etc should stop writing articles about vapour ware GPUs . The biggest European hardware vendor Caseking had no GPUs in stock bar 1060s. It's a joke. GPU vendors are shipping stock to miners. I've a 3700x with a 480rx 8GB. No way am I paying double retail price for a new card, if I could find one. Nividia and Amd could stop this nonsense but no they are scalping their customers. I will remember. Techspot et al need to get on side with their reader base and start kicking up a stink.
 

Irata

Posts: 1,352   +2,164
So AMD is trying to make people upgrade their cpu when there is no real need to do so.
The article is about nVidia‘s implementation. AMD‘s SAM even works with Zen+ CPU and older chipsets, even though it‘s not official.

Either way, I think nVidia‘s implementation shows that supporting resizable bar is perhaps not as trivial as simply enabling a standard PCIe feature like much of the tech press made us believe. AMD started working on this back in 2015 (on Linux).


 

scavengerspc

Posts: 1,078   +1,030
TechSpot Elite
Other will like a rx6000 series....
Ok, Ok Don Corleone of Nvidia cry us a river but I meant no disrespect your GeForce-ness. The very headline of the article says "BAR support for RTX 3000 GPUs". Point Me to the AMD version of this article and I will be sure to only make the comment about AMD. Since it, you know, will be about AMD.

Besides the Asus TUF 6900XT is available on Amazon right now.
 
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NeoMorpheus

Posts: 402   +765
Ok, Ok Don Corleone of Nvidia cry us a river but I meant no disrespect your GeForce-ness. The very headline of the article says "BAR support for RTX 3000 GPUs". Point Me to the AMD version of this article and I will be sure to only make the comment about AMD. Since it, you know, will be about AMD.

Besides the Asus TUF 6900XT is available on Amazon right now.
Suddenly, a nvidia white knight shows up!
 

hahahanoobs

Posts: 3,292   +1,472
AMD did it first so downplay any attempt by anyone else, regardless of the fact AMD doesn't do anything better.

lol Yea, no.

AMD firsts' result in competitors doing it better every time, but yea, fiction is more fun!