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Loihi 2 - Intel
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Loihi 2
intel loihi 2 chip.png
General Info
MarketArtificial Intelligence
IntroductionSeptember 30, 2021 (announced)
September 30, 2021 (launched)
Neuromorphic Specs
ProcessIntel 4
Die31 mm²
Max SMP16,384-Way (Multiprocessor)
Vcore0.50 V-1.25 V

Loihi 2 (pronounced low-ee-hee 2) is the successor to Loihi, a second-generation neuromorphic research test chip designed by Intel Labs that was introduced in late 2021. The chip uses an asynchronous spiking neural network (SNN) to implement adaptive self-modifying event-driven fine-grained parallel computations used to implement learning and inference with high efficiency. The chip is a 128-neuromorphic cores many-core IC fabricated on Intel 4 process and features a unique programmable microcode learning engine for on-chip SNN training.


Introduced in September 2021, Loihi 2 is the successor to Loihi, a neuromorphic research test chip. Like its predecessor, Loihi, Loihi 2 consists of an asynchronous spiking neural network (SNN) meaning instead of manipulating signals, the chip sends spikes along activate synapses. Connections are asynchronous and highly timed-based. Neuromorphic cores containing many neurons are interlinked and receive spikes from elsewhere in the network. When received spikes accumulate for a certain period of time and reach a set threshold, the core will fire off its own spikes to its connected neurons. Preceding spikes reinforce each other and the neuron connections while spikes that follow will inhibit the connection, declining the connectivity until all activities are halted.

Loihi 2 is fabricated on pre-production Intel 4 process and has a total of 1,048,576 artificial neurons and 120 million synapses. In addition to the 128 neuromorphic cores, there are 6 managing Lakemont cores.

Key changes from Loihi[edit]

  • Intel 14 nm -> Intel 4 process
  • 1.10x transistors
  • 0.9x synapses per neuron (120,000,000, down from 130,000,000)
  • 7.7x neurons (1,048,576, up from 131,072)
    • 8192 neurons/0.21 mm² Core (up from 1024 neurons/0.41 mm² Core)
  • 2x microprocessor count (6, up from 3)
  • 3D mesh scaling (from 2D)
  • 32-bit integer payload (from binary)
  • Rich programmable neuron cores
  • 3-factor learning
  • Faster circuits
  • new interfaces
    • gigabit ethernet


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Loihi 2-based neuromorphic system[edit]

Intel developed a series of systems based on Loihi 2 which scale to a large number of Neurons and Synapses.

Oheo Gulch Kapoho Point
PCIe card 4" x 4" Ethernet
1 Chip 8 Chips
120,000,000 Synapses 960,000,000 Synapses
1,048,576 Neurons 8,388,608 Neurons

Oheo Gulch (1 chip, 1M neurons)[edit]

Oheo Gulch is a PCIe card form factor that incorporates a single socketed Loihi 2 chip.

intel Oheo Gulch card.jpg

Kapoho Point (8 chip, 8M neurons)[edit]

Kapoho Point a 4-inch by 4-inch form factor board featuring eight Loihi 2 chips arranged in a 2-stacked (double-sided PCB) 4x4 chips. With eight Loihi 2 chips, Kapoho Point incorporates 1,024 neuromorphic cores with 960,000,000 synapses and 8.4 million neurons.

intel Kapoho Point board.jpg


  • Intel 4 process
  • 2,300,000,000 transistors
    • 128 neuromorphic cores + 6 x86 cores
  • 31 mm² die size
    • Core area 0.21 mm²

intel loihi 2 die shot.png

loihi 2 die (annotated).png


  • Some information was obtained directly from Intel

See also[edit]

Facts about "Loihi 2 - Intel"
core voltage (max)1.25 V (12.5 dV, 125 cV, 1,250 mV) +
core voltage (min)0.5 V (5 dV, 50 cV, 500 mV) +
designerIntel +
die area31 mm² (0.0481 in², 0.31 cm², 31,000,000 µm²) +
first announcedSeptember 30, 2021 +
first launchedSeptember 30, 2021 +
full page nameintel/loihi 2 +
instance ofneuromorphic chip +
ldateSeptember 30, 2021 +
main imageFile:intel loihi 2 chip.png +
manufacturerIntel +
market segmentArtificial Intelligence +
max cpu count16,384 +
nameLoihi 2 +
neuron count1,048,576 +
smp max ways16,384 +
synapse count120,000,000 +
technologyCMOS +
transistor count2,300,000,000 +