NVIDIA’s Grace CPU Unveiled, 72 Arm Cores Based On TSMC 4N Process

Hot Chips 34 has been the event of the month for us (so far). A lot of information has been released such as NVIDIA’s Grace Hopper superchip, NVIDIA’s Hopper GPU and the Birentech BR100

What is NVIDIA’s Grace CPU?

We first heard of the Grace Hopper superchip during NVIDIA’s 2022 GTC Keynote. The mention of a CPU from NVIDIA shocked everyone. The Grace Hopper superchip is essentially a Superchip featuring two chips on one motherboard. One is NVIDIA’s Hopper based GPU and the other is the Grace based CPU. 

Grace Architecture

NVIDIA’s new Scalable Coherency Fabric (SCF) mesh interconnect allows for a massive bandwdith of 3.2TB/s across various Grace chip units. This mesh is scalable for up to 72+ cores where each CPU has 117MB of L3 Cache.  

NVIDIA’s Grace CPU features 72 Arm v9.0 cores designed using TSMC’s 4N process node which is essentially an improved version of the 5nm process. Featuring 25.1 Billion transistors, expect extremely fast computational power. 

NVIDIA Grace CPU Specifications | NVIDIA via Wccftech

NVIDIA is planning to use 512GB LPPDR5x memory for its Grace Hopper superchip. Why, you may ask. 512GB of LPDDR5x memory spread across 32-channels offers the best efficiency/cost saving metrics while performing just as good as the other alternatives. 

NVIDIA’s Memory Choice | NVIDIA via Wccftech

NV-Link Interface

To enable chip-to-chip interlink, NVIDIA introduced its NVLink technology. This interface provides a bandwidth of around 900GB/s which is 7x more than a PCIe 5.0 x 16 interface . NVLink-C2C uses just 1.3 pJ/bit which is 5x more efficient than PCIe Gen 5.0.

InterconnectPicojoules per Bit (pJ/b)
NVLink-C2C1.3 pJ/b
UCIe0.5 – 0.25 pJ/b
Infinity Fabric~1.5 pJ/b
TSMC CoWoS0.56 pJ/b
Foveros0.2 pJ/b
EMIB0.3 pJ/b
Bunch of Wires (BoW)0.7 to 0.5 pJ/b
On-die0.1 pJ/b

Power Consumption

As per NVIDIA, the complete superchip is expected to use around 500W of power. That’s actually impressive considering the power it can offer. AMD EPYC 7763‘s (2x) uses around 560W (280×2) of power, so NVIDIA is actually in lead.

Sadly, even this cannot play Minecraft with RTX ON because NVIDIA states that this superchip has been designed specifically for AI workloads. The Grace CPUs are more pertained towards high performance computing, whereas the Hopper GPU is targeted for AI training, HPC. 

Abdullah Faisal
With a love for computers since the age of give, Abdullah has always sought to delve into the depths of information, and uses it as his guiding light. He believes success is of utmost importance as history is written by the victor.