Tuesday, September 22nd 2020
The Reason Why NVIDIA's GeForce RTX 3080 GPU Uses 19 Gbps GDDR6X Memory and not Faster Variants
When NVIDIA announced its next-generation GeForce RTX 3080 and 3090 Ampere GPUs, it specified that the memory found in the new GPUs will be Micron's GDDR6X variant with 19 Gbps speed. However, being that there are faster GDDR6X modules already available in a 21 Gbps variant, everyone was left wondering why NVIDIA didn't just use the faster memory from Micron. That is exactly what Igor's Lab, a technology website, has been wondering as well. They have decided to conduct testing with an infrared camera that measures the heat produced. To check out the full testing setup and how they tested everything, you can go here and read it, including watching the video embedded.
Micron chips like GDDR5, GDDR5X, and GDDR6 are rated for the maximum junction temperature (TJ Max) of 100 degrees Celsius. It is recommended that these chips should run anywhere from 0C to 95C for the best results. However, when it comes to the new GDDR6X modules found in the new graphics cards, they are not yet any official specifications available to the public. Igor's Lab estimates that they can reach 120C before they become damaged, meaning that TJ Max should be 110C or 105C. When measuring the temperature of GDDR6X modules, Igor found out that the hottest chip ran at 104C, meaning that the chips are running pretty close to the TJ Max they are (supposedly) specified. It is NVIDIA's PCB design decisions that are leading up to this, as the hottest chips are running next to voltage regulators, which can get pretty hot on their own.
The takeaway here is that the heat produced from the card is quite huge with a TGP of 320 W, meaning that the cooling is quite a problem which NVIDIA managed to keep under control, however, the design decisions resulted in some possible performance loss. Instead of NVIDIA using Micron's faster 21 Gbps chips, they are forced to use the 19 Gbps variants. It is not like there would be supply issues as NVIDIA is Micron's only GDDR6X customer, however, the real reason is heat management. The speedup from a slower 19 Gbps chip to faster 21 Gbps chips is plus 10%, meaning that the heat output would follow the percentage, resulting in even greater TGP of the card. The conclusion drawn here is that the current chips are limited by temperature only, as the card is pretty hot, and that is why NVIDIA doesn't use the faster GDDR6X variant.
Sources:
Igor's Lab, via Tom's Hardware
Micron chips like GDDR5, GDDR5X, and GDDR6 are rated for the maximum junction temperature (TJ Max) of 100 degrees Celsius. It is recommended that these chips should run anywhere from 0C to 95C for the best results. However, when it comes to the new GDDR6X modules found in the new graphics cards, they are not yet any official specifications available to the public. Igor's Lab estimates that they can reach 120C before they become damaged, meaning that TJ Max should be 110C or 105C. When measuring the temperature of GDDR6X modules, Igor found out that the hottest chip ran at 104C, meaning that the chips are running pretty close to the TJ Max they are (supposedly) specified. It is NVIDIA's PCB design decisions that are leading up to this, as the hottest chips are running next to voltage regulators, which can get pretty hot on their own.
55 Comments on The Reason Why NVIDIA's GeForce RTX 3080 GPU Uses 19 Gbps GDDR6X Memory and not Faster Variants
This new cutting edge we're getting stinks a little bit, if you ask me.
He did manual overclocks, and found the gpu clock been increase gave basically no performance.
He then boosted memory clock speed and got a measurable increase, it was sub 5% but was there.
Even my 1080ti gets bigger gains from memory clocks vs gpu core clocks, these rumours that memory clock speeds are pointless seem wrong.
The most likely reason the fastest gddr6x chips are not been used is they will instead be used on a future 3000 series product, nvidia dont show their best hand on the early products of a generation. They probably cost more for starters.
I wrote all ready too many hints that they need to follow so the hot pan GPU technology model this to change.
In the product design of RTX 3080, all headroom of support technologies this came at the max.
Power usage this maxed at the point that the use of power limiter to be enforced.
Air cooling system this were developed at max of possible obtained performance due air.
Memory modules which are thermally cooler and use lesser energy were selected.
GPU max frequency which does not cause destructive power usage this is enforced at highest performance variants.
In summary, dear NVIDIA you did succeed to bring your self at 2020 in a DEAD END for any further GPU development.
I bet 1000 Euro that your R&D team today this is pulling their hairs from desperation of what to use so to develop the next BIG thing.