Highly expected: Nvidia has finally started implementing Resizable BAR support, starting with the desktop RTX 3060 and a select few laptops with RTX 3000 series. It may be a bit of a hassle to turn it on, but it’s a free upgrade, so thumbs up.
Variable BAR is a feature of the PCIe standard that enables the system’s CPU to see the entire memory subsystem of the GPU, instead of just a small portion of 256 MB. To implement the feature, low-level support in the CPU, motherboard and GPU is required. AMD, which designed all three, was the first to market with a customizable BAR implementation called SAM (Smart Access Memory).
Putting SAM on a RX 6800 can improve the average frame rate of a game by up to 20%, or impair it by up to 10%. In most titles, however, the feature did almost nothing, which is reflected by the average improvement: only 3%.
It is understandable that Nvidia then follows a different route. Their drivers will leave the Resizable BAR by default, and only turn it on in titles where Nvidia finds it improves performance. At the time of writing, these are eight titles:
- Assassin’s Creed Valhalla
- Battlefield V
- Borderlands 3
- Forza Horizon 4
- Rat 5
- Metro exit
- Red Dead Redemption 2
- Watch Dogs: Legion
In these games, says Nvidia, Resizable BAR can improve performance “from a few percent to 10%.” At the end of 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 is denied by the complexity of enabling the Resizable BAR.
In laptops, the situation is okay, but not great: some laptops will be activated with the Resizable BAR, others will not, and you can do nothing about it. Nvidia says to “go to each laptop manufacturer to see if Resizable BAR is supported on a specific model.”
Desktop Compatibility is a game of 3D chess. Enabling Resizable BAR, or, just as likely, discovering that your system does not support it, is a five-step process. First you need to check if your CPU is compatible: all AMD computers are in the 5000 series, just like all 10th generation Intel processors, but only the i5, i7 and i9 series of the next 11th generation will be compatible. . Simple enough …
Step two: go to the chipset of your motherboard. AMD 500 series chips are compatible (currently undesirable) and the 400-series disk sets are compatible on motherboards that are also compatible with Ryzen 5000 series CPUs. The 500 series chips that Intel’s writing has announced are all compatible, and so are all of their 400 series chips. Still with me?
Step three is more difficult: you need to update the SBIOS of your motherboard, but you just have to hope that an update exists. According to Nvidia, “the following manufacturers offer SBIOS updates for selected motherboards to enable Resizable BAR with GeForce RTX 30 Series graphics cards: Asus, Asrock, Colorful, EVGA, Gigabyte and MSI.”
Fourth, you need to update the VBIOS of your GPU unless you are one of the lucky ones who has a new RTX 3060. For Founders Edition owners, Nvidia will provide the update itself, but all others will update their GPU manufacturer’s page.
And the home range: upgrade your GPU drivers. After that, you can check in the Nvidia control panel within the System Information tab whether the Resizable BAR is working correctly.