AMD Radeon Smart Access Memory Review - 22 Games Tested

erek

Supreme [H]ardness
Joined
Dec 19, 2005
Messages
6,988
"Our launch-day coverage of the Radeon RX 6800 series includes: Radeon RX 6800 XT Review, Radeon RX 6800 Review, AMD Smart Access Memory Review.

By now, if you've read our full Radeon RX 6800 XT review, you'll know that AMD has gained solid ground in performance, and the days of intense Radeon vs. GeForce competition are back. The RX 6800 XT averages just 2% behind the RTX 3080 at 1080p, just 1% behind at 1440p, but 6% behind—as tested on a machine powered by a Ryzen 9 5900X, these gaps are different in our main review, which is using an Intel processor.

Enabling Smart Access Memory (SAM) is enabled by toggling a switching in the UEFI setup program of a compatible motherboard—if you've satisfied the requirement of a Ryzen 5000 series processor and AMD 500-series chipset motherboard. With SAM enabled, we see the averages change "dramatically" (in context of competition), with the RX 6800 XT now being 2% faster across all three resolutions. This helps the RX 6800 XT match the RTX 3080 at 1080p, while beating it by 1% at 1440p, and being just 4% slower at 4K UHD—imagine these gains without even touching other features such as Radeon Boost or Rage Mode!

It's important to understand that SAM doesn't work with all game engines. In "Borderlands 3," and "Divinity" for example, SAM negatively impacts performance. It seems that SAM comes with a small CPU overhead, which will cause a loss in FPS in games that are CPU bound, because the CPU is losing time dealing with SAM, time that it can't handle frame rendering. In certain other games, there's zero impact (eg: DOOM Eternal). In certain games, though, such as "Gears 5," there are significant frame-rate gains seen with SAM enabled, which help tilt the averages in favor of SAM being enabled.

Overall, SAM isn't snake oil per-se, it offers tangible performance gains that are surprisingly large, considering nobody cared about the resizable BAR feature for years. We only wish that AMD hadn't restricted it to only its latest platform, and the latest processor. If AMD's excuse is "we want to maximize PCIe Gen 4 bandwidth utilization, Gen 3 would post bottlenecks," then our retort would be "what about Ryzen 3000 Matisse?" What about Intel's "Rocket Lake" which comes out next year? The restriction to Ryzen 5000 seems arbitrary.

NVIDIA has already announced that they will add a similar feature to their GeForce graphics cards, probably with wider platform support. I'm sure this will lead AMD to open their discovery to more chipsets and hardware combinations. Enabling the feature requires you to boot in UEFI mode. If you've been denying UEFI like I have, and rather use CSM and MBR, then the time to switch has come, the performance gains finally justify it.

If you're one of the lucky few who flew to the horn of Africa, joined a pirate gang, hijacked a Maersk superheavy, broke into the right container, and pulled out a Ryzen 5000 processor, then Smart Access Memory is a cool feature to have (no, don't do that)."


https://www.techpowerup.com/review/amd-radeon-sam-smart-access-memory-performance/
 

MrGuvernment

Fully [H]
Joined
Aug 3, 2004
Messages
19,603
Finally, some real reviews, not the marketing hyper that NVIDIA and AMD spew making everyone think their cards will demolish the competitions..
 

erek

Supreme [H]ardness
Joined
Dec 19, 2005
Messages
6,988
anyone else catch wind of this?

Coil whine​

The reference cards do exhibit coil squeal. Is it annoying? It's at a level you can hear it. In a closed chassis, that noise would fade away in the background. However, with an open chassis, you can hear coil whine/squeal. Graphics cards all make this in some form, especially at high framerates; this can be perceived.


(i know the 3090 FE has some coil whine too, anymore it's charming?)
 

TheSlySyl

Gawd
Joined
May 30, 2018
Messages
754
Wish I knew why this was limited to 5000 series CPUs and not available for 3000 series.
I get why it would require PCI-E 4.0, so the chipset requirement kinda makes sense....
 

Brackle

Old Timer
Joined
Jun 19, 2003
Messages
7,715
Wish I knew why this was limited to 5000 series CPUs and not available for 3000 series.
I get why it would require PCI-E 4.0, so the chipset requirement kinda makes sense....
IT works on PCI-E 3.0 motherboards as well. I think Hardware Unboxed said they tried it and it worked.

I think its more of an AMD limitation. Nvidia has already come out to say SAM will work on their Ampere cards soon, and be supported by Intel and AMD. Intel is still on PCI-E 3.0
 

whateverer

[H]ard|Gawd
Joined
Nov 2, 2016
Messages
1,382
IT works on PCI-E 3.0 motherboards as well. I think Hardware Unboxed said they tried it and it worked.

I think its more of an AMD limitation. Nvidia has already come out to say SAM will work on their Ampere cards soon, and be supported by Intel and AMD. Intel is still on PCI-E 3.0


Right, this is just adjusting the PCIe BAR memory window size.

https://stackoverflow.com/questions/20901221/pci-express-bar-memory-mapping-basic-understanding

We've been waiting for the 32-bit era to officially end, before it makes sense to increase the memory window above 256MB (and they likely made it window = VRAM size, since you can virtually-address 64 bits of ram.)

This should have exactly the same performance improvement, regardless of the video card brand.
 

Marees

Gawd
Joined
Sep 28, 2018
Messages
843
Borderlands 3 is a game where the RX 6800 XT already does well, and it was highlighted in AMD's reviewer's guide as being a title that really benefits from Smart Access Memory - so let's give it a try.

We see very little difference between our Intel and AMD test systems at 4K, but turn on Smart Access Memory and the AMD platform gets out to a four per cent lead - not bad!
This lead lengthens at 1440p to eight per cent,
then again at 1080p to a mighty 12 per cent.

That's a really respectable return, pushing the game at its highest settings from one that can max out a 144Hz monitor to one that can do the same with a 165Hz monitor.

Note however that our lowest one per cent scores actually worsen slightly with SAM engaged, something that persisted after several retests, so that's something to keep an eye on.

https://www.eurogamer.net/articles/digitalfoundry-2020-amd-radeon-rx-6800-and-6800-xt-review?page=6

So there you have it - some big gains in Borderlands 3 and non-RT Control, but unfortunately we don't see significant improvements in the other titles we tested that could shift the RX 6800 XT into closer contention with the RTX 3080.

And contrary to our expectations, it looks like it's actually the lower resolutions, 1080p and 1440p, where the technology seems to be most effective, although the extra horsepower is needed more at 4K.
 

chameleoneel

2[H]4U
Joined
Aug 15, 2005
Messages
3,738
Borderlands 3 is a game where the RX 6800 XT already does well, and it was highlighted in AMD's reviewer's guide as being a title that really benefits from Smart Access Memory - so let's give it a try.

We see very little difference between our Intel and AMD test systems at 4K, but turn on Smart Access Memory and the AMD platform gets out to a four per cent lead - not bad!
This lead lengthens at 1440p to eight per cent,
then again at 1080p to a mighty 12 per cent.

That's a really respectable return, pushing the game at its highest settings from one that can max out a 144Hz monitor to one that can do the same with a 165Hz monitor.

Note however that our lowest one per cent scores actually worsen slightly with SAM engaged, something that persisted after several retests, so that's something to keep an eye on.

https://www.eurogamer.net/articles/digitalfoundry-2020-amd-radeon-rx-6800-and-6800-xt-review?page=6

So there you have it - some big gains in Borderlands 3 and non-RT Control, but unfortunately we don't see significant improvements in the other titles we tested that could shift the RX 6800 XT into closer contention with the RTX 3080.

And contrary to our expectations, it looks like it's actually the lower resolutions, 1080p and 1440p, where the technology seems to be most effective, although the extra horsepower is needed more at 4K.
I'm guessing that the presumed latency improvements from being able to address all of the memory aren't as important at 4K/GPU limited scenarios. Because 4K requires more GPU time anyway. So the extra time it takes to address memory without SAM is sort of absorbed into the 16ms frametimes for 60fps. and SAM therefore isn't as big a factor at conventional framerates.

But higher refresh scenarios where the GPU is not the limit, benefit rather well. Because being able to address all of the memory is usually going to be a speed benefit and support the higher framerates. And later, when better GPUs come out which are less limited at 4K, we will undoubtedly see better scaling for SAM at 4K.

I would guess the lower minimums can be ironed out with a game and/or driver patch. AMD has mentioned that both SAM and infiinity cache benefit from organizing game data in ways which suit the technology. And if game devs oblige, we could see bigger and/or more consistent gains. I'm assuming that stellar RDNA2 performance of Dirt 5, Godfall, and AC: Valhalla are due to exactly that. Devs working with AMD to organize the game data to suit their tech.

As the new console generation moves forward, I wonder if most games might do this almost by default. Especially games which are on Xbox. Because Xbox runs on a version of Direct X.
 
Last edited:
Top