WhoBuilt

What If We Stopped Using GPUs?

Oct 2, 2026· 1 h 21 min· 75K views·Watch on YouTube

An unnamed Y Combinator host and three presenters discuss alternatives to GPU based AI computing at an Alternative Compute Club event: optical computing with Ilker, neuromorphic hardware with Aloque, and cultured brain cells with Sean.

Why explore alternatives to GPUs

The host traces how deep learning hardware shifted from optimizing FLOPs to prioritizing memory capacity and bandwidth for transformers. He argues that gains in FLOPs per joule have slowed and points to the brain’s roughly 20 watt power use as motivation to explore other approaches. He also outlines a proposal called SOMA: train small, specialized LSTM experts on clustered data and combine them at inference.

Optical computing for image generation

Ilker explains how light can carry information with low loss and high bandwidth, and how passive optical systems can perform parallel linear operations. He describes an application specific optical device for diffusion based image generation, using repeated light propagation to denoise images; tests used small datasets such as MNIST and Fashion MNIST. The reported energy advantage depended on fixed, passive weights, while data conversion, calibration, nonlinear operations, and optical memory remain challenges.

Neuromorphic computing principles and directions

Aloque describes neuromorphic computing as borrowing principles such as intertwined memory and computation, event driven signals, mixed analog and digital behavior, and adaptation through learning. He says the field remains in R&D, with work spanning digital memory near compute, spiking systems for real time edge tasks, and devices such as memristors and coupled oscillators. He identifies memory and compute integration as a nearer term direction, while more brain like approaches remain early.

Using cultured neurons to play Doom

Sean describes treating cultured brain cells as a changing input output system: an encoder converts Doom observations into electrical stimulation, and a decoder maps the cells’ spikes to game actions. He says the encoding and decoding must be learned for a complex game, and warns that an oversized decoder can appear to perform well while doing the work itself. Feedback uses synchronous or asynchronous stimulation, scaled by surprise; Sean says how to scale biological computing for broad service remains an open question.

Takeaways

  • Match the algorithm to the hardware’s strengths; optical computing is most promising when data conversion and weight updates are limited.
  • Measure the full system energy budget, including conversion, calibration, memory, and nonlinear operations.
  • Keep decoders small enough to confirm that the biological or specialized component contributes to performance.
  • Treat neuromorphic computing as a broad research area, and separate near term memory and compute integration from early brain inspired systems.
  • For biological computing, scaling from a working demonstration to reliable service remains an unresolved engineering problem.

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What was claimed 9

  • received
    $125,000 for winning a competition
    “They gave us $125,000 for winning some competition”
    YouTube
    Unverified1 source· Talk
  • feature
    SPSA: Estimates updates from forward passes on randomly perturbed parameters without calculating gradients
    “there's no gradient, so I can optimize zero-one loss landscapes completely fine”
    YouTube
    Unverified1 source· Talk
  • feature
    SOMA: Clusters data and trains a small expert model per cluster, then routes among the models at test time
    “I call SOMA: sharded optimization mixture of assemblies”
    YouTube
    Unverified1 source· Talk
  • feature
    fiber optics: Passive optical propagation can perform massively parallel linear operations
    “it is massively parallelizable because photons don't interact with other photons”
    YouTube
    Unverified1 source· Talk
  • feature
    Lightmatter: Electrical-optical PCIe board with compute numbers comparable to GPUs
    “shows an electrical-optical PCIe board with compute numbers comparable to GPUs”
    YouTube
    Unverified1 source· Talk
  • uses
    “programming optical propagation as a denoising or generation inference unit”
    YouTube
    Unverified1 source· Talk
  • metric
    Standard: $1.5 billion in assets under management
    “We have one and a half billion in assets under management”
    YouTube
    Unverified1 source· Talk
  • feature
    neuromorphic computing: Applies brain organizing principles such as intertwined memory and computation, spikes, and adaptation to circuit design
    “borrow the brain's organizing principles when designing circuits, chips, and other things we use to compute”
    YouTube
    Unverified1 source· Talk
  • feature
    D-Matrix: Brings SRAM close to compute through co-packaging
    “bringing SRAM much closer in the memory hierarchy to the compute on the decode side”
    YouTube
    Unverified1 source· Talk

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