Intel has just announced that if you won’t be able to install one of ARC graphics cards without ResizableBAR on your motherboard. A jug of cold water that may not be so cold and may become a trend by other manufacturers. Especially from AMD, its direct rival. Why have you made this decision and what advantages and disadvantages does it have?
The news that ARC Alchemist graphics cards won’t work without Resizable BAR active on the motherboard is something that has to be interpreted as the empty glass paradox. Intel’s interest is to sell both its processors and its graphics and motherboards in tandem. So it is a way of joining two elements, not through the support of said functionality, but through what it allows. However, the performance benefits are potentially greater.
Traditionally, the PC is a system that in order to organize the RAM memory of different components, this is of the NUMA type. Which translates to being in the same common memory pool. However, the arrival of heterogeneous chips that brought a central processor and graphics card in a single component changed things in that particular case. Thus, instead of having two separate physical memories, they now have one in common. How do you make it so that one component doesn’t write to another’s memory space? Well, a part of the RAM capacity is assigned to the CPU and the rest that is missing to the GPU.
Well, one of the peculiarities that Resizable BAR has is that it allows the processor to see all the memory space assigned to the graphics card, whether it is in a separate memory or in the same memory. Which means that for practical purposes of the driver, which runs on the CPU, you can see the entire memory pool allocated to the integrated GPU in your Core processors and the one used as RAM as a single block. However, they have taken this a little further with their gaming graphics cards.
Why do Intel ARCs need ResizableBAR?
First of all, and before anything else, despite the negative tone of this information, we must start from the basis that ReBAR is available from PCI Express 3.0 and many motherboards on the market already support it and can be activated from the BIOS options. The reason why Intel has decided that you cannot use its ARC graphics cards without ResizableBAR is not for performance issues, but because one of the spearheads of its graphics is called Deep Link.
The usual idea is that if we have a dedicated graphics card, the one inside the processor will turn off, however, Intel’s idea is to take advantage of the Resizable BAR function so that the iGPU does asynchronous tasks. That is, supportive, but independent of frame creation. And what use would it be? Well, for things like:
- If you are streaming games on Twitch or YouTube, you can use the integrated graphics and its video codecs as a video capture + encoder without the need for any additional hardware.
- In calculations related to the physics of games and the detection of collisions of some object, both graphs can collaborate to speed it up and gain a few more frames without effort.
It is a functionality that is more useful than you think. And since AMD placed a lot of importance on ReBAR in the form of its Smart Access Memory, we have no doubt that we could see the same requirement in the Ryzen 7000. NVIDIA’s decision? We do not know it, since they do not sell central microprocessors and it is more difficult for them to coordinate both parts.