Where are the video memory? The thing on the video card

Yesterday's push "to understand the memory you do not know" under a small partner message, can spread the memory of knowledge. Xiaobian said today that the memory is better.

Before talking about memory, we must first talk about the function and role of the graphics card. The video card is the bridge between the computer and the monitor. Through it, the computer's graphical interface can be sent to the display and displayed correctly. Everyone knows that the monitor has different resolutions, and this resolution is actually the number of pixels that the monitor can draw. For example, 1920×1080 means a total of 2,073,600 pixels. A graphic image is sent by the computer CPU to the graphics card GPU, and then the screen is calculated and output to the display. During this process, the video memory is required to store the calculated content, and finally output to the display, filling each pixel, To form the final picture, the effect of initial memory is also limited to this.

With continuous development, the displayed image is no longer just a 2D image that is outlined by colors or lines. For example, various effects of 3D games will be “accumulated” on the display and even some of them cannot be displayed on the screen. The content is also calculated by the graphics card GPU (for example, a human body, all his structures will be calculated, the more detailed the screen needs to calculate the "triangle", the more GPU performance and memory need more and more). There will be very, very much more data.

And because the picture is dynamic, it means that the data volume of each frame is refreshed in real time, and more and more memory will be used during this period. For example, what frame buffer, back buffer, Z-axis buffer, texture data, and geometry data are stored in the frame buffer are what is seen on the screen; and the background buffer is the second frame buffer, which stores the contents of the next frame; Z The axis cache is used to store the data needed for the Z-axis operation, reducing the amount of GPU computation; the final texture data and geometric data determine the quality and special effects of the game. It is worth mentioning that if the user turns on anti-aliasing technology in the game, since the anti-aliasing technology requires more sampling, the data capacity of the actual game stored in the video memory will also increase exponentially, so video memory is not only required to be faster. Faster, more and more capacity.

Not only that, memory is similar to memory, there is a very important technical indicator called "bit width", and the memory bit width is the number of bits that can be transmitted within one clock cycle. The larger the number of bits, the faster it can be transmitted. The greater the amount of data. At present, the lowest-end graphics card is 64-bit wide, followed by 128-bit. High-end graphics cards generally have 256-bit and even 384-bit width (GDDR5, GDDR5X), and even HBM2 memory can reach a staggering 2048 bits!

Memory and GPU complement each other. It's not enough to have the most intuitive feeling of memory. That is to say, is it easier for you to understand something? As for the current graphics card, you can see that the video memory in the mid-range graphics card is generally about 3GB, the entry-level graphics card is 1GB to 2GB, and the high-end products are basically kept between 6GB and 8GB. 10GB memory.

In addition, video memory is now dominated by GDDR5, GDDR5X and HBM, and HBM2, especially for the former two applications. When you buy a video card, you can see that NVIDIA and some AMD graphics cards use GDDR5 and GDDR5X memory cards. Among them, AMD uses less HBM/HBM2 video memory for a few graphics cards (the latest released VEGA video card is HBM2 video memory).

In essence, HBM memory has a higher bandwidth performance and is a technical alternative to GDDR5 memory. The increase in bandwidth is very large, but the capacity has not been up until HBM2 solves this problem. However, the cost of HBM2 memory is still very expensive, and there is still a long way to go before it is truly popular. So when you buy a video card, you do not need to consider whether it is HBM2 memory.