On the GPU front, NVIDIA is actually using a slightly better version of their venerable GA102 GPU, which now is used across 5 different desktop video cards. The version of the GA102 used here has a slight increase in the number of SMs enabled versus the OG RTX 3080, with 70 SMs as opposed to 68 on the original card. Clockspeeds have also changed a bit; while the official boost clock rating is still 1.71GHz, the base clockspeed for the new SKU is 1.26GBz, 180MHz below the more basic 3080. Ultimately this seems to be a function of TDP, as the additional memory and additional transistors being lit up on the GPU will increase the power needs of the card, especially in a maximum-load scenario.
As for the memory, the increase to 12GB of GDDR6X comes with a matching increase in the width of the memory bus. The RTX 3080 12GB sees GA102’s full 384-bit memory bus enabled, reflecting the addition of 2 more GDDR6X memory chips (64-bits) to the memory bus, bringing the total to 12 chips/384-bits. According to NVIDIA’s specifications, they’re using the same 19Gbps GDDR6X chips here as on the classic RTX 3080, so memory clockspeeds have neither been dialed up or dialed down. So the expansion of the memory bus brings with it both an additional 2GB of VRAM – which will come in handy at 4K – as well as a 20% increase in memory bandwidth. Compared to the 10GB RTX 3080 and its 760GB/second of memory bandwidth, the 12GB RTX 3080 offers 912GB/second of bandwidth.
But to pay the bill for all of this, so-to-speak, the TDP of the newer 12GB SKU is also higher than the 10GB cards. Here NVIDIA’s official/minimum TDP has gone from 320W to 350W, a 9% increase. And as we noted before, even with this TDP increase, the minimum/base clockspeed still needed to be turned down a bit. This gives the RTX 3080 12GB the same official TDP ratings as both the RTX 3080 Ti and RTX 3090, and if these values are accurate, then it implies that the new card will have the lowest energy efficiency out of all of them.