MSI GeForce RTX 4090 SUPRIM X & SUPRIM Liquid X Review – When Air & Water Collide!

NVIDIA Ada GPU - GDDR6X Memory Subsystem Deep Dive

The Micron GDDR6X memory brings a lot of new stuff to the table. It is faster, doubles the I/O data rate, and is the first to implement PAM4 multi-level signaling in memory dies. With the Geforce RTX 3090 class products, Micron's GDDR6X memory achieves a bandwidth of up to 1 TB/s which is used to power next-generation gaming experiences at high-fidelity resolutions such as 8K.

Micron GDDR6X graphics memory doubles input/output (I/O) performance while minimizing the cost of memory. Working with AI-innovation leader NVIDIA, Micron delivers higher bandwidth by enabling multi-level signaling in the form of four-level pulse amplitude modulation (PAM4) technology in this memory device via Micron

The new GDDR6X SGRAM:

• Doubles the data rate of SGRAM at a lower power per transaction while enabling the breaking of the 1 Terabyte per second (TB/s) system memory bandwidth boundary for graphics card applications;

• Is the first discrete graphics memory device that employs PAM4-encoded signaling between the processor and the DRAM, using four voltage levels to encode and transfer two bits of data per interface clock.
• Can be designed and operated stably at high speeds and built-in mass-production.

As mentioned, GDDR6X features the brand new PAM4 multilevel signaling techniques, which help transfer data much faster, double the I/O rate, pushing the capability of each memory dies from 64 GB/s to 84 GB/s. The Micron GDDR6X memory dies are also the only graphics DRAM that can be mass-produced while featuring PAM4 signaling.

What is interesting is that Micron quotes that its GDDR6X memory can hit speeds of up to 22.4 Gbps whereas we have only got to see 21 Gbps in action on the GeForce RTX 3090 Ti. It is likely that AIBs could utilize higher binned dies as they are available. Micron does has faster chips but those aren't coming to NV 40 series graphics cards for now.

It's not just faster speeds but Micron's GDDR6X provides higher bandwidth while sipping in 15% lower power per transferred bit compared to the previous generation GDDR6 memory. PAM4 signaling is a big upgrade from the two-level NRZ signaling on the GDDR6 memory.

Instead of transmitting two binary bits of data each clock cycle (one bit on the rising edge and one bit on the falling edge of the clock), PAM4 sends two bits on each clock edge, encoded using four different voltage levels. The voltage levels are divided into 250 mV steps with each level representing two bits of data - 00, 01, 10, or 11 sent on each clock edge (still DDR technology).

Micron GDDR6X Memory

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