Much more on GDDR6x from Toms Hardware:
Micron Reveals GDDR6X Details: The Future of Memory, or a Proprietary DRAM?
By Anton Shilov a day ago
Micron discusses graphics memory: GDDR6X is here, PAM4 & PAM8 for HBM patented
Micron Technology shared some additional details about its latest GDDR6X SGRAM used by Nvidia's GeForce RTX 30-series graphics cards at a virtual briefing last week. The company revealed that it has experimented for more than a decade with technologies enabling the new type of memory and said that GDDR6X SGRAM had not been standardized by JEDEC yet. Right now, only Nvidia uses GDDR6X memory, but Micron hopes this will change over time. Can it?
PAM4 Signaling: Explored for DRAM Since 2006 Micron's Graphics DRAM Design Center in Munich, Germany, has a history of graphics memory innovation ever since the design center belonged to Qimonda, a long-gone DRAM spinoff from Infineon. Engineers from these labs brought the industry's first GDDR5, GDDR5X, and now GDDR6X chips to mass production. In fact, Micron was the only maker of GDDR5X, and now it is the sole producer of GDDR6X.
Four-level pulse amplitude modulation (PAM4) signaling is the key feature of GDDR6X memory. This technique transmits two data bits per cycle using four signal levels, thus doubling the effective bandwidth for any operating frequency vs. previous-generation SGRAM types. In addition, PAM4 opens doors to higher data transfer rates (albeit at a cost). As a result, PAM4 improves both efficiency-per-clock and speeds.
There is a slight caveat, though. GDDR6 has a burst length of 16 bytes (BL16), meaning that each of its two 16-bit channels can deliver 32 bytes per operation. GDDR6X has a burst length of 8 bytes (BL8), but because of PAM4 signaling, each of its 16-bit channels will also deliver 32 bytes per operation. To that end, GDDR6X is not faster than GDDR6 at the same clock....
Nvidia is Micron's only GDDR6X launch partner, but Micron stresses that it didn't design the new type of memory exclusively for the GPU developer. The DRAM maker plans to offer GDDR6X to other companies, too.
"We now start offering and opening this up to the industry, GDDR6X is not customer-specific," said Ebert. "We expect other customers to have interest moving forward, and then we will also engage with them."
....
Speaking of power, it is necessary to note that because of considerably increased performance, GDDR6X is 15% more power-efficient than GDDR6 (7.25 pj/bit vs 7.5 pj/bit) at the device level, according to Micron.
Overall, GDDR6X chips and their implementation is more expensive than GDDR6, but it is still considerably cheaper than HBM2-class memory, according to Micron. GDDR6X does not require stacking, and it's shipped as discrete chips that can be soldered down at a factory. The whole infrastructure for discrete DRAMs has existed for decades, and all processes are familiar and cheap. By contrast, HBM2 KGSDs (known-good stacked dies) have to be assembled at a semiconductor fab and then placed on an interposer next to a GPU in a cleanroom of another fab.
"Higher performance DRAM typically also comes at a higher cost," said Ebert. "The big advantage of GDDR6X is that we could push the bar of performance much higher while still remaining within a certain cost envelope. This is given by the fact that GDDR6X is still a discrete memory solution. The GDDR6X memory can be assembled like any other memory on a PCB by add-in-board makers in their standard environment. When you look into the different speed grades of memory, there's typically ranges in cost adders; we positioned our GDDR6X in line with typical ranges. This is not a product that comes at an extremely higher cost for the customer, mainly due to the fact because it is still a discrete memory solution."
Micron doesn't disclose the die size of its 8 Gb GDDR6X devices and doesn't compare it to its 8 Gb GDDR6 devices. The company emphasizes that this is the first type of memory to use PAM4 signaling, and the latter is a breakthrough that opens doors to various kinds of innovation.
"PAM4 was a challenge, and we believe that with this breakthrough, this can be done moving forward," said the director of graphics DRAM at Micron. "This will, we believe, change the DRAM industry. We were the first ones to have done this, and we have been working on this for quite a while."
much more at tomshardware.com
This seems like a big deal. |
