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GDDR5 (Graphics Double Data Rate Type 5)

Graphics Double Data Rate 5 Synchronous Dynamic Random-Access Memory (GDDR5 SDRAM) is a type of synchronous graphics random-access memory (SGRAM) with a high bandwidth (“double data rate”) interface designed for use in graphics cards, game consoles, and high-performance computing. It is the fifth generation in the GDDR series, succeeding GDDR4 SDRAM.

GDDR5 is based on DDR3 SDRAM memory, which has double the data lines compared to DDR2 SDRAM, allowing for faster data transfer and increased performance. It uses an 8N-prefetch architecture and a DDR interface to achieve high-speed operation. The GDDR5 interface transfers two 32-bit wide data words per write clock (WCK) cycle to and from the I/O pins, corresponding to the 8N-prefetch. This means that each GDDR5 memory chip can send or receive data twice per clock cycle, effectively doubling the data rate compared to previous generations.

The memory operates with two different clock types: the differential command clock (CK) used as a reference for address and command inputs, and the forwarded differential write clock (WCK) used as a reference for data reading and writing. The WCK’s operating frequency is twice that of the CK, which helps to increase the bandwidth and speed of the memory.

GDDR5 SGRAM is single-ported but can open two memory pages at once, simulating the dual-port nature of other VRAM technologies. This feature, along with its high bandwidth and speed, makes GDDR5 suitable for applications requiring fast and efficient processing of large amounts of graphical data.

Commercially, GDDR5 was first introduced by Samsung Electronics and Hynix Semiconductor, with mass production starting in 2008. It has been widely adopted in the industry and used in various high-end graphics cards and gaming consoles[1][5].

Key features of GDDR5X:

Increased Bandwidth: GDDR5X provides a transfer rate of 10 to 14 Gbit/s per pin, which is twice that of GDDR5. This increased bandwidth allows for more data to be transferred per second, enhancing the performance of graphics cards[1][2].
Prefetch Architecture: GDDR5X can operate in two modes: a double data rate (DDR) mode with an 8n prefetch and a quad data rate (QDR) mode with a 16n prefetch. The 8n prefetch is the same as GDDR5, while the 16n prefetch in QDR mode is a new feature that allows for 64 bytes per read or write, doubling the amount of data fetched per cycle compared to GDDR5[1][3].
Voltage Improvements: GDDR5X uses 1.35V for both core logic and I/Os, compared to GDDR5 which allowed 1.35V or 1.5V. The pump voltage (Vpp), which is used for internal memory operations, is also reduced from 3.3V in GDDR5 to 1.8V in GDDR5X, contributing to power efficiency[3].
Physical Package: GDDR5X uses a 190 ball grid array (BGA) package, which is different from the 170 BGA package used by standard GDDR5. This change requires a modified printed circuit board (PCB) design to accommodate the new memory chips[1][3].

Commercialization and Adoption

GDDR5X was standardized by JEDEC in January 2016 and began to see commercial use shortly thereafter. Micron Technology started sampling GDDR5X chips in March 2016 and began mass production in May 2016. The first graphics card to use GDDR5X was the Pascal-based GeForce GTX 1080, announced by Nvidia on May 6, 2016[1].

Citations:

[1] https://en.wikipedia.org/wiki/GDDR5_SDRAM

[2] https://semiconductor.samsung.com/dram/gddr/gddr5/

[3] https://www.pcmag.com/news/ddr5-vs-ddr4-how-much-performance-will-you-gain-from-todays-newest-ram

[4] https://forums.tomshardware.com/threads/what-does-gddr5-mean.3034768/

[5] https://www.minitool.com/lib/gddr5.html

[6] https://www.tomshardware.com/features/ddr5-vs-ddr4-is-it-time-to-upgrade-your-ram

[7] https://en.wikipedia.org/wiki/DDR5_SDRAM

[8] https://media-www.micron.com/-/media/client/global/documents/products/white-paper/ddr5_new_features_white_paper.pdf

[9] https://www.pugetsystems.com/labs/articles/impact-of-ddr5-speed-on-content-creation-performance-2023-update/

[10] https://www.pcmag.com/encyclopedia/term/gddr

[11] https://www.rambus.com/blogs/get-ready-for-ddr5-dimm-chipsets/