This is not o3; it is what they'd internally called Orion, a larger non-reasoning model.

They say this is their last fully non-reasoning model, but that research on both types will continue.

It's currently limited to Pro users, but the model hasn't yet shown up on the chooser, despite them announcing it. They say it will be shared with Plus users next week.

It claims to be more accurate at standard questions and with a lower hallucination rate than any previous OAI model (and presumably any others).

Here's the start of the system card:

OpenAI GPT-4.5 System Card

OpenAI
February 27, 2025

1 Introduction

We’re releasing a research preview of OpenAI GPT-4.5, our largest and most knowledgeable model yet. Building on GPT-4o, GPT-4.5 scales pre-training further and is designed to be more general-purpose than our powerful STEM-focused reasoning models. We trained it using new supervision [...]

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Outline:

(00:44) OpenAI GPT-4.5 System Card

(00:54) 1 Introduction

(02:21) 2 Model data and training

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First published:

Source:

Narrated by TYPE III AUDIO.