When we look at our graphics cards, the type of memory used is of increasing interest. The latest evolution has brought about a slightly more powerful version of GDDR6X supplied by Micron. An evolution that can support up to 1 TB/s of bandwidth used on the new RTX 4090. The maximum seems to be 24 Gbps for these chips. It seems that on this subject we have reached a ceiling, an evolution towards a new generation is inevitable, it is the GDDR7. Samsung is on it and has just mentioned the potential of these future chips and some characteristics. The first point concerns the speed that GDDR7 memory will be able to reach quickly: 36 Gbps. If we compare it to the current GPU, here are a few calculations to realize the interest: On a memory bus of 256 bits, using a GDDR7 memory of 36 Gbps, we will obtain 1152 Gbps of memory bandwidth. If we put ourselves in the conditions of a high-end GPU (like the one of the 4090 for example) with 384-bit memory interfaces, we get 1728 GB/s of memory bandwidth.
The other point is more technical and indicates that GDDR7 will use a different modulation called PAM-3. The GDDR6 uses NRZ (Non Return to Zero) with an information of 1 bit / cycle or PAM-2, the PAM-3 modulation allows to provide 3 bits on 2 cycles, which will allow to transfer more information. Finally, these various changes should also improve energy efficiency by 25%. But in the absence of a reference, it is difficult to give an opinion on this subject.
Finally, from a more practical point of view, the arrival of GDDR7 does not seem to be scheduled before 2024 on “classic” products.
