Samsung has announced that it has completed development of the world’s first GDDR7 chip. The memory has a data transfer rate of 32 GT/s, uses pulse amplitude modulation (PAM3) and promises a 20% improvement in power efficiency compared to GDDR6.
At a data rate of 32 GT/s, GDDR7 has a bandwidth of 128 GB/s, which is significantly more than the 89.6 GB/s per chip provided by GDDR6X at 22.4 GT/s. The 32GT/s 384-bit GDDR7 memory subsystem delivers a whopping 1,536 TB/s of bandwidth, well above the 1,008 TB/s of the GeForce RTX 4090.
To achieve unprecedented high speed, GDDR7 uses PAM3 pulse amplitude modulation with three different signal levels (-1, 0 and +1). This mechanism allows three bits of data to be transmitted in two cycles, which is more efficient than the two-level NRZ used in GDDR6. However, it is important to note that PAM3 signals are more difficult to generate and decode than NRZ (which means additional power consumption) and may be more susceptible to noise and interference. But it looks like the benefits of PAM3 outweigh its problems, so it will be adopted for GDDR7 and USB4 v2.
GDDR7 memory is 20% more energy efficient than GDDR6, although Samsung hasn’t specified a method to measure this. Typically, memory manufacturers measure the power per bit transmitted.
However, this does not mean that GDDR7 memory chips and controllers will consume less than GDDR6. PAM3 encoding is more complex and requires more power. Samsung is talking about using an epoxy molding compound (EMC) with high thermal conductivity and 70% lower thermal resistance for the GDDR7 packaging to ensure the active components don’t overheat. This indicates a stronger heating of the GDDR7 memory, especially when running at high clock speeds.
Samsung did not say when it plans to start mass production of GDDR7 and what process will be used. Given the announcements of new graphics architectures from AMD and NVIDIA every two years, it is logical to expect that graphics cards with GDDR7 will hit the market in 2024.
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Source: Tom’s Hardware