GDDR7 SDRAM

This article is about DDR graphics RAM (SGRAM). For non-graphics (dynamic) DDR memory, see SDRAM.

Graphics Double Data Rate 7 Synchronous Dynamic Random-Access Memory (GDDR7 SDRAM) is a type of synchronous graphics random-access memory (SGRAM) specified by the JEDEC Semiconductor Memory Standard, with a high bandwidth, "double data rate" interface, designed for use in graphics cards, game consoles, and high-performance computing. It is a type of GDDR SDRAM (graphics DDR SDRAM), and is the successor to GDDR6.

GDDR7 SDRAM
Graphics Double Data Rate 7 Synchronous Dynamic Random-Access Memory

Type of RAM
PCB of the NVIDIA GeForce RTX 5090D with sixteen GDDR7 chips (16 Gibibit each)
Developer	JEDEC
Type	Synchronous dynamic random-access memory
Generation	7th generation
Release date	March 5, 2024; 14 months ago (2024-03-05)
Predecessor	GDDR6 SDRAM

History

• At Samsung Tech Day 2022, Samsung announced GDDR7 as the successor of GDDR6X, which could deliver up to 36 GT/s.^[1] Samsung announced two months later that it would use PAM-3 signaling to achieve the highest transfer rate.^[2]
• On March 8, 2023, Cadence announced the verification solution tool for preliminary GDDR7 SDRAM production.^[3]
• On June 30, 2023, Micron announced that it will be manufactured using 1β node (equivalent to 12–10 nm process node), slated to release in H1 2024.^[4]
• On July 18, 2023, Samsung announced the first generation of GDDR7, which can reach up to 32 Gbps per pin (100% higher bandwidth per pin compared to 16 Gbps per pin on GDDR6), 40% higher bandwidth (1.5 TB/s) compared to GDDR6 (1.1 TB/s) and 20% more energy efficient. For packaging material, it will use epoxy molding compound (EMC) along with IC architecture optimization, which will reduce thermal resistance by 70%.^[5] Later, on a Q&A session, Samsung mentioned that it will be manufactured using D1z node (equivalent to 15–14 nm^[6]) and will operate on 1.2V. A 1.1V version with reduced clockspeeds will also be made available at some point in to the future after the release of the 1.2V version.^[7]
• On March 5, 2024, JEDEC published the GDDR7 Graphics Memory formal standard and specifications.^[8]

Technologies

GDDR7 SDRAM employs three-level (-1, 0, +1) pulse-amplitude modulation (PAM-3) instead of NRZ in GDDR6 and PAM-4 in GDDR6x. PAM-3 enables the transfer of three bits of data within two cycles, while NRZ transfer of one bits of data within one cycle. PAM-3 is 20% more energy-efficient than NRZ while running at a higher bandwidth. Manufacturing equipment will be less costly than PAM-4.^[9]

GDDR7 adds on-die error correction code, error checking and scrubbing features for chip reliability, mainly useful for compute/AI use cases.^[10]

Initial data rates are at 32 Gbps/pin, while memory manufacturers have noted that rates up to 36 Gbps/pin are readily attainable. The standard has future bandwidth up to 48 Gbps/pin,^[11] and chip capacities up to 64 Gbit - compared to GDDR6X's 16 Gbit.^[10]

See also

• List of interface bit rates