NVIDIA PCI-Express Resizable BAR Performance Test - 22 Games, 3 Resolutions, RTX 3090, 3080, 3070, 3060 Ti

Armenius

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TechPowerUp has tested resizable BAR performance on Ampere cards across all games that support it in their current testing suite. They found that the performance delta can vary wildly between games and resolutions, with resolution obviously playing a big role. They show how resizable BAR can be enabled on other games through NVIDIA Inspector, but per usual there may be bugs and anomalies that could pop up in titles that are yet to be officially supported.

Out of our 22 game test suite, that's 12 titles, which is pretty decent. The gains vary wildly, though—around 20% (!!) in Gears 5 and almost nothing in other titles. On average, we saw a 2–4% performance improvement from Resizable BAR when counting titles with BAR support in the driver. Now, we of course have 10 more titles in our test suite without BAR support, which drags down the overall average, but I feel that looking at "BAR-only" games is the better approach since almost every title will benefit from Resizable BAR, it's just a matter of game support. While "a few percent" doesn't sound like much, it's free extra performance for a minimal investment and no loss in image quality. I wish I had insight into how many man-hours GPU makers spend on BAR support vs. traditional driver game optimizations.

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https://www.techpowerup.com/review/nvidia-pci-express-resizable-bar-performance-test/
 

Balkroth

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Glad to see it out, I enabled it once the drivers came out. Glad to see there's at least some difference.
 

wyqtor

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Which CPUs does this work on?

And am I correct in assuming they aren't going to bother retrofitting it for Turing.
 

criccio

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Which CPUs does this work on?

And am I correct in assuming they aren't going to bother retrofitting it for Turing.

From the AMD camp, Ryzen 3000 "Zen 2" and Ryzen 5000 "Zen 3" processors support it. On the Intel camp, hardware support technically dates back to the 4th Gen "Haswell," but most motherboard vendors for whatever reason restricted their Resizable BAR enabling BIOS updates to the 300-series chipset, or 8th Gen "Coffee Lake" (and later) architectures, along with X299, or 7th Gen "Skylake-X" HEDT (and later).
 

MaZa

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This was good news. I did update my Mobo and GPU bios yesterday and installed new drivers and made sure it was turned on. Not much use of it yet though as the first game I started to play was Stardew Valley. Had a hectic easter holiday and I just wanted to wind down with a calm, relaxing game... 🤣 But it is now ready for all the future games that make use of it. Now I just want to see reviews comparing Nvidia's rebar and AMD's SAM and how/if they differ in how much performance boost it gives.
 
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zehoo

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Looks like the small bump in gaming performance I expected.

The real question though is left unanswered. What's the increase in hash rate, since most of the rtx3XXX stock is in miners' hands.
 
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Saabjock

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Unlocking 'overlooked and previously untapped' performance with software is not a bad thing, unless somehow you deem it necessary to increase price for doing so.
 

Archaea

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Looks like the small bump in gaming performance I expected.

The real question though is left unanswered. What's the increase in hash rate, since most of the rtx3XXX stock is in miners' hands.
No hash rate increase according to son of tech on YouTube.

 
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toast0

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Now I just want to see reviews comparing Nvidia's rebar and AMD's SAM and how/if they differ in how much performance boost it gives.

It's the same feature, expanding the gpu mapping in system address space so all the ram is mapped directly, so I wouldn't expect much difference, unless one side was particularly bad at memory windowing/paging/whatever it's called for GPUs.

The real question though is left unanswered. What's the increase in hash rate, since most of the rtx3XXX stock is in miners' hands.

I wouldn't expect much; mining doesn't do a lot of data transfering, so even if you can make that a little bit better, it's not going to make a big difference.
 
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