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The bit depth of video card must exactly match bit depth of video memory. As we all know, main components of a video card are GPU and video memory, so-called video memory bandwidth can be understood as bandwidth of channel through which data is transferred from video memory to GPU, i.e. throughput of conveyor belt of workshop.

Because everyone pays too much attention to amount of video card memory when buying a computer, many people ignore importance of width of memory interface, and there are even 2 GB discrete graphics cards with only 64 bits that are deceiving video cards. Someone may say that it would be better if bit depth of video card was greater. It's wrong, expanding video card's capacity requires expanding hardware, just like you want to expand road and occupy land, so cost is much higher than that of increasing video memory. Therefore, usually video cards with high bit depth are much more expensive.

So, someone asked, how do I know if my graphics card has correct bit depth? Here is a simple formula for calculating minimum bit depth:

Minimum video memory bandwidth = (x48x8 resolution)/(video memory frequency)

Firstly, modern computers tend to operate in 32-bit true color display mode. In this mode, each pixel requires 16 + 32B of data to render, of which first 16B is used for base rendering, and last 32B is for texture rendering. If our screen is a 1080p 1920x1080 screen, then data stream required to render whole screen once is: 1920x1080x48B=99532800B=94.92MB, for a normal LCD screen, each pixel is updated 60 times per second. , so required data flow per second is 94.92 MB x 60 = 5.695 GB. In a word, this is minimum requirement for a video card to maintain a normal screen display.

We are assuming that graphics card's memory frequency is 1250 MHz, which is not too low for DDR3 memory, which means that memory reads and writes 1250 million times per second, and each data transfer corresponds to memory interface width / 8, (Unit memory interface width is a bit, data flow should use B, 1B=8 bits), if memory interface width is 64 bits, then graphics card's maximum data flow is 1250Mx64/8=10GB. In other words, it is able to display normally.

But note that this is only a requirement to maintain normal screen display. If you play games, texture calculation will be much higher and it will reach several times normal data. Then basic graphics of map data stream will not be normal at this time. Execution, monitor can only reduce frame rate to display, and freezer will appear after frame rate decreases to a certain extent. Therefore, I personally recommend that you buy a video card that exceeds minimum bit depth requirements several times.

For example, if someone buys a 4K screen, data rate they need per second is about 4 times that of a 1080p screen, which is about 24 GB. At this time, if video memory frequency is 1250 MHz, required bit width is 157 bits, which is minimum requirement. So if you really plan to buy a supercomputer with a 4K screen, then it is better to equip it with a video card with a 512-bit memory interface width. Of course, this is for DDR3 video memory. If your video card has DDR5 video memory, then video memory frequency can reach 5000 MHz. Currently, you only need 40 bits to ensure minimum image requirements. This is why bit depth of some video cards with DDR5 memory is much smaller than that of video cards with DDR3 memory.

Finally, let's talk about method for calculating minimum video memory bandwidth:

Minimum video memory bandwidth = (x48x8 resolution)/(video memory frequency)