Intel Promises Arc A770 Will Launch Very Soon But Be Wary If You're Not Running Resizable BAR
Intel's Ryan Shrout and Tom "TAP" Petersen are on the trail again for the release of the Arc A770 and A750 GPUs. The pair were recently in Berlin, Germany, and spoke with German site PC Games Hardware (PCGH) as well as popular YouTube nitpickers Digital Foundry. There were a few interesting take-aways from the conversations that Intel had with the two outlets, but none moreso than the acknowledgement that Arc practically requires support for resizable BAR.
If you're left wondering what that is, well, let me explain. BAR stands for "base address register," and it is a space in memory reserved for accessing the local memory on an expansion card like a discrete GPU. Traditionally the BAR has been limited to 256 MB, which means that the CPU can only write to GPU memory in 256MB chunks before the BAR window has to be moved. This adds overhead when using the CPU to do graphics-related work, something that all games do.
Resizable BAR, or "re-BAR" as it is known, allows the graphics driver (or potentially even game software) to re-size this window to whatever size is appropriate. This reduces overhead and improves latency for certain types of workloads, particularly gaming. By the way, AMD calls this feature SmartAccess Memory, but it's the same thing.
Besides a GPU and drivers that support the feature, using re-BAR also requires a CPU and platform that are capable of it. Generally speaking, with the latest BIOS updates, it should be supported on any Ryzen CPU from AMD's 5000 or 6000 series, most Ryzen 3000-series processors, and just about any Intel CPU from the 10th-gen onward, as long as the motherboard vendor has issued the proper BIOS updates. You'll also have to turn it on in UEFI setup—make sure you disable the legacy CSM and enable Above 4G Decoding, as those are also required.
So now we come back around to Intel. The message from TAP when speaking to both Digital Foundry and PC Games Hardware is that while it isn't literally a requirement, you can think of re-BAR support as a requirement for Arc Alchemist graphics cards. That's because, as prior testing has shown, the performance drops off a cliff without this feature enabled.
As Digital Foundry's Rich Leadbetter points out, the majority of PCs out there right now, even those used for gaming, do not have re-BAR support. If you're still hanging onto a perfectly serviceable 8th- or 9th-gen Intel machine or using a Ryzen 1000/2000 processor, you're out of luck when it comes to both re-BAR and Arc Graphics.
In those cases, Intel's messaging is pretty clear: "stick to another vendor." Those are the specific words of TAP himself, who means that if you can't use re-BAR, don't buy an Arc GPU, as it won't be a pleasant experience for you. Testing has shown that performance falls off by as much as 40%, with much of the performance loss coming in the particularly undesirable forms of microstutter and hitching.
Other interesting tidbits from the interviews include that the Arc A770 will apparently fall between the Radeon RX 6600 and RX 6600 XT. That puts it in more-or-less the same territory we saw before, where it beats the RTX 3060 in ray-tracing workloads. The top-end model will be available in 16GB and 8GB configurations, while the one-step-down A750 will only come with 8GB of memory.
If you're chomping at the bit to go blue for your GPU, Intel says that there will be limited supplies of the A770 and A750 available from its website at launch. However, they'll only be available in "certain countries" initially. The only one that the boys confirmed is Germany, but we'd obviously expect the US to be on that list as well.
As for when that launch is actually happening, well, they still didn't say aside from cheekily mentioning that it would be "very soon now." Pricing also wasn't discussed, but your author's money is on $399 for the 16GB A770.