A user from the Chiphell forums has evaluated the impact of Resizable BAR on Nvidia's flagship GeForce RTX 3090. While the results aren't phenomenal, the extra performance comes free of charge, so we welcome it with open arms.
While Nvidia has pledged to bring Resizable BAR to its entire stack of Ampere graphics cards, only the more recent GeForce RTX 3060 comes with a vBIOS that's primed for the feature. Other Ampere offerings will need an updated vBIOS to enjoy the same benefits. Nvidia and its partners are expected to release vBIOS updates for their corresponding graphics card tomorrow. However, Galax and Gainward have already started deploying the new updates, which has enabled the Chiphell forum user to test the Resizable BAR feature ahead of everyone else.
Resizable BAR is only supported on Nvidia's Ampere offerings. On the platform side, however, support includes AMD and Intel platforms, more specifically the 400-and 500-series chipsets from both chipmakers. In terms of processors, AMD's Zen 3 and Intel's Comet Lake and Rocket Lake are on the compatibility list. Many motherboard manufacturers have released new firmware to support Resizable BAR on Ampere so there shouldn't be any issues there.
Nvidia GeForce RTX 3090 Resizable BAR Benchmarks
The Chiphell user's testbed was based on a Ryzen 9 5950X processor that was paired with 32GB of memory and a GeForce RTX 3090 Founders Edition graphics card. He did his testing at the 4K (3840 x 2160) resolution.
Currently, only a few titles support Resizable BAR with Ampere. The short list includes Assassin's Creed Valhalla, Battlefield V, Borderlands 3, Forza Horizon 4, Gears 5, Metro Exodus, Red Dead Redemption 2 and Watch Dogs: Legion. The user tested all, but Battlefield V since it doesn't come with a built-in benchmark tool.
| Game | Resizable BAR Off | Resizable BAR On | Difference |
|---|---|---|---|
| Assassin's Creed Valhalla | 69.00 | 72.00 | 4.3% |
| Borderlands 3 | 80.09 | 81.60 | 1.9% |
| Forza Horizon 4 | 175.00 | 181.00 | 3.4% |
| Gears 5 | 86.30 | 89.20 | 3.4% |
| Watch Dogs: Legion | 62.00 | 65.00 | 4.8% |
| Red Dead Redemption 2 | 73.62 | 74.47 | 1.2% |
| Metro Exodus | 66.29 | 66.29 | 0% |
According to the results, Resizable BAR provides the GeForce RTX 3090 with performance boosts anywhere between 1.2% and 4.8%, depending on the game. If you want to put that into a single number, we're looking an at average of 3.2%. Of course, there are some titles, such as Metro Exodus that won't benefit from Resizable BAR whatsoever.
As minor as the improvement may be, it's free so it doesn't hurt to enable Resizable BAR even though it's a placebo in some occasions. The Chiphell user performed his tests at 4K so the performance gains could be higher at lower resolutions at 1440p (2560 x 1440) or 1080p (1920 x 1080) since the graphics card will be less bottlenecked. We'll be doing some testing of our own shortly so don't forget to check back.
