WhoBuilt

The Engineering Unlocks Behind DeepSeek

Feb 5, 2025· 13 min· 214K views·Watch on YouTube

Y Combinator host explains the engineering behind DeepSeek’s V3 and R1 models, and what their efficiency gains mean for AI builders.

V3 is the foundation for R1

DeepSeek V3 is a general-purpose model released in December 2024, while R1 is a reasoning model built on top of V3. The host says R1 reached performance comparable to OpenAI o1 and Google Flash 2.0 on some complex reasoning benchmarks. Many of the techniques behind the models appeared in DeepSeek papers published earlier in 2024.

Making GPU compute go further

V3 was trained in FP8, with periodic FP32 accumulation to limit numerical errors while using less memory. Its mixture-of-experts design has 671 billion parameters but activates 37 billion per token, and multi-head latent attention reduces KV cache storage. Multi-token prediction adds training signals and can also support faster generation.

Training reasoning with reinforcement learning

DeepSeek used reinforcement learning on problems with verifiable answers, especially in math and coding, scoring final answers with simple accuracy and formatting rules. Its GRPO method updates the model from those scores without supplying examples of how to reason. Reasoning emerged over thousands of steps, but the initial R1-Zero outputs mixed languages and were hard to read, so DeepSeek added a structured reasoning fine-tuning phase.

What the cost and attention figures leave out

The host notes that R1 performed comparably to o1 on some math and coding benchmarks, while OpenAI’s o3-mini soon outperformed both on key benchmarks. R1’s free access and lower cost helped draw attention, but the reported $5.5 million for V3 covered only its final training run, not R1 training, research, or hardware operating costs. The host says a Berkeley lab reproduced key R1-Zero techniques in a smaller model for $30.

More room to build across the AI stack

The host argues that DeepSeek shows there is room for new companies to improve GPU workloads, inference software, tooling, and AI-generated kernels. Lower intelligence costs could benefit consumer and business applications. The episode closes with a YC Spring Batch application deadline of February 11.

Takeaways

  • Measure model efficiency across the full workload, including memory, networking, and GPU utilization.
  • Mixture-of-experts models can reduce per-token computation by activating only part of their parameters.
  • Use verifiable tasks and simple outcome-based rewards when training models to solve problems.
  • Treat reported training-run costs as partial figures unless they include research, hardware, and later training.
  • Falling inference costs create opportunities for products that were previously too expensive to run.

Mentioned in this talk

Search inside this talk

What was claimed 23

  • metric
    DeepSeek-R1: Claimed performance comparable to OpenAI o1 at a fraction of the cost
    “it claimed achieved performance comparable to OpenAI o1 at a fraction of the cost”
    YouTube
    Unverified1 source· Talk
  • metric
    Nvidia: Nearly $600 billion in market capitalization lost in one day
    “Nvidia losing nearly $600 billion in market cap in a single day”
    YouTube
    Unverified1 source· Talk
  • launched
    “DeepSeek recently made waves when it announced R1, an open-source reasoning model”
    YouTube
    Verified4 sources· Talk
  • feature
    DeepSeek: Publishes research and releases model weights
    “publishing its research and releasing its model weights for months”
    YouTube
    Unverified1 source· Talk
  • metric
    DeepSeek-R1: Performance comparable to OpenAI o1 and Google Flash 2.0 on certain complex reasoning benchmarks
    “performance comparable to OpenAI o1 and Google Flash 2.0 on certain complex reasoning benchmarks”
    YouTube
    Unverified1 source· Talk
  • feature
    DeepSeek-R1: Reasoning model optimized for complex reasoning
    “applied various algorithmic improvements to optimize its reasoning ability”
    YouTube
    Unverified1 source· Talk
  • uses
    “DeepSeek R1...is a reasoning model built on top of DeepSeek V3”
    YouTube
    Unverified1 source· Talk
  • launched
    general-purpose base model
    “DeepSeek V3, which was actually released this past December”
    YouTube
    Unverified1 source· Talk
Show all 23 facts

Related talks