Intel says it will bring Resizable BAR to 11th-gen Rocket Lake CPUs

nanoguy

Posts: 894   +12
Staff member
In brief: Hardware manufacturers AMD, Intel, and Nvidia have been working on incorporating a new performance-boosting feature that has been part of the PCIe spec for years called Resizable BAR (resizable Base Address Register). It's been demonstrated that by allowing the dynamic expansion of the data channel between the CPU and the graphics memory, you can squeeze some additional performance from your setup.

Resizable BAR defines how much of your graphics cards VRAM is to be mapped for access by the CPU. Typically the CPU can access up to 256 MB of mapped VRAM, but with the resizable BAR it can have full access to the graphics cards' VRAM buffer.

AMD already added support for Resizable BAR (calling it SAM or "Smart Access Memory") for specific systems running both a Ryzen 5000 CPU paired with a Radeon RX 6000 series graphics card. We've tested the feature and surely it can bring some visible performance increases in titles like Assassin's Creed Valhalla, Borderlands 3, Dirt 5, The Division 2, Hitman 2, and Godfall. However in some other titles it either saw zero benefit or even a marginal loss of performance.

AMD tried marketing this as a "unique" technology, but what it really should have said was that unless you buy its latest hardware, you're practically out of luck. Nvidia and Intel have since promised to roll out the feature to other system configurations.

For those of you who prefer Intel - Nvidia setups or happen to have paired an Intel CPU with an AMD graphics card, things are a bit more complicated, since Intel only started offering support for Resizable BAR with 11th-gen Rocket Lake desktop CPUs on Z490 motherboards last December.

Some motherboard manufacturers such as MSI and Asus have promised that they will eventually bring this to other platforms including some that are limited to 8th-gen Intel CPUs, but you'll still need to use a Radeon 6000 series graphics card or one of Nvidia's RTX 3000 series, both of which are in short supply and will become even harder to acquire in the coming months.

For laptop gamers, Intel this week announced during the Tom's Hardware Show that it will bring Resizable BAR to systems equipped with 11th-gen Tiger Lake CPUs and H35-series mobile chipsets, as well as systems equipped with 10th-gen Comet Lake-H CPUs and H45-series chipsets.

The company didn't offer an exact timing, but pointed out that in its internal testing it found that some games are seeing performance gains of 5 to 10 percent. OEMs are currently getting close to validating BIOS and driver updates to enable Resizable BAR, but since cryptocurrency miners are snatching the newest gaming laptops to cope with the shortage of desktop graphics cards, it will be a while before you can see this "free" performance boost for yourself.

Overall, it's good to see that Intel, Nvidia, and AMD are working together to make Resizable BAR a standard feature on modern systems, even if in the short term it will require an upgrade that is either costly, not in stock, or both.

Permalink to story.

 

hahahanoobs

Posts: 3,599   +1,710
Prime X470 Pro Beta BIOS
Improve ReSizable BAR compatibility for NVIDIA RTX30 series graphics cards
 

Irata

Posts: 1,657   +2,774
Resizable BAR (SAM) already works on Zen 2 and even Zen+ CPU with < 500 series mainboards.

https://www.computerbase.de/2020-12/amd-smart-access-memory-renoir-matisse-b450/

You might want to take that into consideration.

As for the rest, yes it‘s a standard PCIe feature, but you know how it went with sliced bread - both slicing and bread were standard features, yet someone was first to sell a product combining the two.
 

GamerNerves

Posts: 100   +53
RBAR showed to be more beneficial feature than I expected, but it's stupid that it is for now only supported on the latest GPU generation, since those cards are the ones that cost still too much even at MSRP, because the cheaper models are not out, and they will be likely not that widely used in the end if people just wait and skip the generation due to the availability issue. So many people have GeForce 1600/2000 or Radeon 5000/500 series card, so those really need this feature the most, or rather the slower your GPU the more you benefit from the feature. I hope Nvidia and AMD will widen support soon enough.
 

PurpleYoda

Posts: 146   +121
So... is it already available on RTX cards? My MSI Mobo got an update to support it but I was under the impression the nVidia is yet to release a Bios update to take advantage.. Did I miss the fact they already did as the article suggests that being the case?
 

Irata

Posts: 1,657   +2,774
So... is it already available on RTX cards? My MSI Mobo got an update to support it but I was under the impression the nVidia is yet to release a Bios update to take advantage.. Did I miss the fact they already did as the article suggests that being the case?

It seems to work / be a feature in XMG Ryzen + RTX 3060 laptop, so for mobile it‘s at least available:

https://www.techspot.com/review/2193-geforce-rtx-3060-laptop/

Why this was not mentioned here as the article was also done by Techspot is a sad omission. May not be a bad idea if some articles were proofread as there seems to be room for improvement.
 

Shadowboxer

Posts: 1,717   +1,322
All the corporations here, Intel, AMD and Nvidia have used a feature of PCIe3 to push sales. But it can work on all PCIe3 boards and cards.

So I have an X570 board and an RTX 2080. But because Nvidia appear to be using this feature to push sales for 30xx I don’t get it. Same with anyone on an older AMD or Intel motherboard, AMD or Intel could give it to you but they want you to buy their latest hardware so they don’t. AMD even had the bloody cheek to market it as an exclusive on their platform.

It’s quite annoying.
 

HardReset

Posts: 1,236   +887
So I have an X570 board and an RTX 2080. But because Nvidia appear to be using this feature to push sales for 30xx I don’t get it. Same with anyone on an older AMD or Intel motherboard, AMD or Intel could give it to you but they want you to buy their latest hardware so they don’t. AMD even had the bloody cheek to market it as an exclusive on their platform.

It’s quite annoying.

Everything wrong there as usual.

BAR requires video card BIOS support. GeForce 2000 series is already 2.5 years old. Do you expect Nvidia could force card manufacturers to offer new vBIOS' for 2.5 year old cards? For this kind of "not so essential feature", no.

For AMD and Intel motherboards, it's entirely up to motherboard manufacturers. Not much AMD or Intel can do about it.

AMD's Smart Access Memory is AMD only feature. However AMD didn't market anywhere that resizable BAR support is AMD only feature. While those things are essentially same, AMD can call their own version what they like and say it's AMD only. Because it is.