Train a Reasoning Model for $1.23 (Reinforcement Learning)

CES 2026 spotlighted “reasoning” models as the next frontier — but you don’t need a supercomputer to build one. Here’s the exact Reinforcement Learning (RL) pipeline I used to train a GSM8K reasoning model for $1.23. 📺 New here? Start with the $0.62 video: https://youtu.be/zY8cPov5R6M 📓 Notebook / Code: https://github.com/LLM-Implementation/Practical-LLM-Implementation/blob/main/hpc-ai/hpc_ai_sql_finetune.ipynb 🤝 Sponsored by HPC-AI (free credits link/code below) 💸 THE COST BREAKDOWN • Text-to-SQL SFT (Qwen3-8B): $1.03 • RL Reasoning (Qwen3-4B on GSM8K): $1.23 ✅ Total Spend: $2.26 🧠 WHAT WE’RE BUILDING You don’t need a massive cluster to run a real RL reasoning loop. I’ll show you how to train Qwen3-4B on GSM8K using RL (after warming up with a production Text-to-SQL SFT run on Qwen3-8B) using the HPC-AI SDK. 📌 WHAT YOU’LL LEARN 🛠️ HPC-AI SDK — Write local Python loops that execute on a remote GPU cluster 🔥 SFT Warmup — Build a production Text-to-SQL agent on Qwen3-8B 🧪 RL Reasoning — Trajectory grouping + reward functions on Qwen3-4B (GSM8K) ⏱️ Cost Hacking — How a ~4-hour RL loop cost only $1.23 (active compute only) ⚠️ The RL Pitfall — Why SFT plateaus, and how grouped rollouts select better trajectories 🧬 MODELS & DATA • SFT: Qwen/Qwen3-8B-Instruct (Text-to-SQL) • RL: Qwen/Qwen3-4B-Instruct (Math/Reasoning) • Datasets: GSM8K (RL), 10k Text-to-SQL pairs (SFT) • Infra: Remote GPU clusters via HPC-AI SDK 🚀 GET $10 FREE CREDITS (First 100 Users) Sign up here: https://www.hpc-ai.com/account/signup?invitation_code=llm_impl Invite Code: llm_impl 📚 SDK DOCS https://www.hpc-ai.com/fine-tuning ⏱️ CHAPTERS 00:00 AI Engineering for the price of a coffee 00:38 Free Credits (Sponsor: HPC-AI) 00:51 What is the HPC-AI SDK? (Local Logic, Cloud Compute) 01:52 Environment & API Setup 02:31 Result 1: Text-to-SQL SFT (Qwen3-8B) — $1.03 03:29 The “Magic” Loop: Forward/Backward Remote Execution 04:14 Result 2: RL Reasoning Agent (Qwen3-4B) — $1.23 04:32 RL Confi