The specifications for the GDDR7 memory standard for graphics cards are published by JEDEC – the Computer Foundation

Next generation memory It is expected to be widely used In the future, directly interested companies such as AMD, Micron, NVIDIA, Samsung, and SK hynix have positioned themselves on this topic through relevant announcements and press releases. According to estimates, the new type of GDDR7 memory (the standard is officially called JESD239 Graphics Double Data Rate SGRAM) will initially be used in the next generation of high-end RDNA 4 and Blackwell graphics cards from AMD and NVIDIA respectively, which are rumored to be released next year.

It's been almost six years since the first graphics cards with GDDR6 memory appeared. If you remember, NVIDIA's GeForce RTX 20 “Turing” series graphics cards were first released in September 2018. The GeForce RTX 2080 and RTX 2080 Ti graphics cards feature 14 Gbps (14 Gbps) GDDR6 memory, providing 56 GB/s per device. Later solutions like AMD's Radeon RX 7900 XTX have memory speeds of up to 20 Gbps providing around 80 Gbps.

NVIDIA later helped create and make available the fastest GDDR6X solution, which started at 19 Gbps in the GeForce RTX 3080 and eventually reached 23 Gbps in the latest GeForce RTX 4080 Super. Officially, Micron states that GDDR6X memory is capable of delivering up to 24 Gbps, which equates to 96 Gbps per device.

GDDR7 will deliver a huge increase in bandwidth from generation to generation. JEDEC specifications indicate that we will see bandwidth of up to 192 GB/s per device. This in turn corresponds to a memory speed of 48 Gbps, twice as fast as the faster GDDR6X memory. However, it is worth noting that the speeds mentioned above are “achieved” in a different way than previous memory solutions.

JESD239 GDDR7 is the first JETEC DRAM standard to use a pulse amplitude modulation (PAM) interface for high-frequency operations. The PAM3 interface improves signal-to-noise ratio (SNR) for high-frequency operation while enhancing power efficiency. By using 3 signal levels (+1, 0, -1) to transmit three bits per two cycles versus the traditional NRZ (Non Return to Zero) interface used for example in GDDR6 memory which transmits two bits per two cycles, PAM3 provides a higher data rate per cycle which results in To significantly improve performance. This change alone, i.e. using the PAM3 interface instead of NRZ, represents a 50% improvement in data transfer performance, meaning that clocks do not need to be doubled compared to GDDR6 clocks. It also introduces the new standard:

• Basic independent LFSR (Linear Feedback Shift Register) training modes with eye masking and error counters to improve training accuracy and reduce training time.

• Doubles the independent channels from two in GDDR6 to four in GDDR7.

• Supports densities ranging from 16GbE to 32GbE, including support for dual-channel operation to double system capacity.

• Meet the market needs for RAS (reliability, availability and serviceability) by incorporating the latest data integrity features, including on-the-run ECC (ODECC) with real-time reporting, error checking and cleanup (Scrub) and command address parity with command blocking (CABARBLACK) .

NVIDIA's next-generation graphics cards based on the “Blackwell” architecture are expected to use GDDR7 memory when they are released. Professional versions of Blackwell or data center graphics cards will almost certainly also be released in late 2024 or early 2025, however they are not expected to use GDDR7 memory but rather HBM3E. We know that AMD is also currently working with RDNA 4 GPUs, and we expect it to use GDDR7 as well (though, don't be surprised if low-end graphics cards from both companies still use GDDR6 or GDDR6X memory for cost reasons). ).

In any case, whether it's an AMD or NVIDIA graphics card, using GDDR7 memory “running” at the highest speeds can provide up to 2304 GB/s of bandwidth by taking advantage of today's wider 384-bit memory bus. Will we really take advantage of this bandwidth? Probably not, if we see low memory chips. When will we see the first graphics cards with GDDR7 memory? Maybe at the end of this year or early 2025.