SK hynix introduced its GDDR7 graphics memory in July 2024 after completing development that March. It announced 32 Gb/s per data pin, with up to 40 Gb/s under certain conditions, and said a high-end graphics card could exceed 1.5 TB/s of memory bandwidth. The company also redesigned the package to help heat leave the device. At the time, it planned to start volume production in the third quarter of 2024. These were claims about the product it introduced, not specifications automatically shared by every later ordering code.
What 32 Gb/s and 1.5 TB/s actually measure #
The two figures describe different levels of the system. The 32 Gb/s figure is a transfer rate at a data pin. The bandwidth of a complete graphics card also depends on how many data lines connect its memory to the GPU. At 32 Gb/s, a 256-bit bus would have a theoretical maximum of 1.024 TB/s; a 384-bit bus would reach 1.536 TB/s. The wider-bus example explains how a card could pass the 1.5 TB/s mark, although SK hynix did not specify the bus width of the card in its announcement. Neither calculation is a measured result from a game or computing workload.
SK hynix also reported approximately 60% higher speed and more than 50% better power efficiency than its previous GDDR generation. Better efficiency does not mean the total power consumption of a graphics card falls by 50%. Likewise, “up to 40 Gb/s” describes a conditional capability, not a speed guarantee for every GDDR7 device or board.
The interface has to carry those faster signals reliably. GDDR7 uses three-level PAM3 signaling. In a subsequent technical explanation, SK hynix described a T-coil approach to reduce high-frequency signal loss and a separate write-clock scheme to control data timing. The memory chip, GPU controller and traces on the card must work together at those rates. A speed headline cannot establish what an existing board will achieve with a particular device.
Why SK hynix changed the package #
Faster transfers also make heat removal more demanding. SK hynix increased the number of heat-dissipating substrate layers in the package from four to six and used epoxy molding compound, or EMC, while keeping the product size unchanged. The company reported a 74% reduction in thermal resistance compared with its previous generation. The molding compound protects the chip; the substrate and package construction influence the path by which heat leaves it.
Thermal resistance is distinct from the power-efficiency figure. Lower thermal resistance makes it easier for heat to move out of the device; it does not mean the chip operates at a temperature 74% lower. Device power, the card's cooling system, airflow and board layout still determine the operating temperature. The package improvement helps make high transfer rates practical, but the finished card still needs its own thermal validation.
SK hynix also named AI, high-performance computing and autonomous driving as possible uses beyond high-end graphics cards.
Two specific GDDR7 devices are H57G42MP2AX006N (16 Gbit) and H57GD2MP23X009N (24 Gbit).