The GPT-5.6 Sol preview has been available for just over half a month, and the first batch of user beta reports are finally here!
NVIDIA's chief engineer tells you in the most straightforward, no-nonsense way:
Sol is amazing! In just 30 hours, it achieved the same CUDA acceleration results that Opus took 64 hours to reach.
After future optimizations, it may completely surpass Opus...
Netizens weren’t idle either—they got creative, coming up with all sorts of comparisons:
When building a spacecraft, look at the interior corridor of GPT-5.6—the color scheme and lighting choices exude a strong sense of technology, with well-defined light and shadow contrasts. In contrast, GPT-5.5’s palette leans warm and gray, making the overall scene appear flatter and more reminiscent of a company locker room.
Not to mention the cosmic scene outside the spaceship—GPT-5.5 looks like a mosaic party. (doge)
This round goes to GPT-5.6!
To explain why GPT-5.6 has surged in popularity again, it’s partly because its longtime rival, Fable 5, has made a comeback, and partly because the model has finally—finally—moved!
After waiting so many days, news has finally emerged that the model will officially launch in the next two days.
At that time, it won’t be available only to a select few "partners"—this time, everyone can access it!
(The waiters won~)
Ultraman himself jumped in to show off, bringing the atmosphere to its peak:
My eldest son spoke his first two-word phrase for the first time ever—the shock I felt was exactly the same as when GPT-5.6 discovered a new mathematical theory.
No issues! They're all my own (doge)
The results of the first beta test are in.
After reviewing posts from beta users, several consensus points emerged.
First, as the previous NVIDIA engineer mentioned: the code is more concise, with less overall code.
For the same requirement, other models might write pages of code, but Sol is notably more restrained—solving it in three lines rather than five, with only one-fifth the line count of Opus. Especially in C++, its style closely resembles human-written code and includes fewer comments.
For projects requiring long-term maintenance, the advantage lies with Sol.
Of course, there are still some drawbacks in the coding—for example, the iterative progress is relatively slow, and the number of failures is higher, because Sol always attempts more challenging tasks.
Compared to Opus, it also has fewer trial-and-error explorations; once it commits to a direction, it pursues it relentlessly.
In simple terms, the model has moved away from massive blind trial-and-error and instead focuses on long-term, in-depth optimization—prioritizing core performance improvements over superficial output results.
This also aligns well with OpenAI's positioning of Sol—
Designed for challenging reasoning tasks, complex code, and other long-chain processes, particularly suited for complex workflows requiring planning, iteration, tool usage, and step coordination.
Using the same prompt and comparing the results between Sol and GPT-5.5 Pro is also very clear:
Sol excels in instruction following and spatial reasoning, offering superior consistency whether for interactive SVGs, 3D models, or generative games.
In terms of frontend design, Sol has also delivered a cleaner, more organized result.
Compared to GPT-5.5, Sol’s page layout and spacing are exceptionally well-executed, with a more refined visual design. Sol easily earns a top score in visual appeal.
Did you successfully sniper Fable 5?
However, the question netizens are most concerned about—how does it compare to Fable 5?
The effect may still be slightly inferior.
On some benchmarks, Sol and Fable 5 score equally or even surpass Fable 5, but there is still a noticeable gap in overall model experience and code quality.
For example, netizen Gipp conducted a comparison of 3D FPS games.
While GPT 5.6 is still struggling to adapt to game worlds, lighting, and mechanics, Fable 5 can already turn a single prompt into a playable, finished game.
However, Fable 5 is significantly more expensive, costing $10 per million input tokens and $50 per million output tokens, while Sol's input cost is only $5 per million tokens and its output cost is $30.
Sol is almost half the price!
Therefore, when model capabilities are similar, it’s hard to say which one will come out on top between Sol and Fable 5.
Even more concerning are the security restrictions: since Fable 5 was sanctioned, users have clearly noticed that Fable 5 isn’t doing any work at all since its return.
Writing code and debugging normally can easily trigger the system’s high-risk detection, causing tasks to be downgraded to Opus 4.8 for handling—even questions like “how many r’s are in ‘raspberry’” get blocked.
Netizens gave Fable 5 a negative review...
On GPT-5.6, the situation is somewhat better. The official team has confirmed that a more robust security system has been implemented, and different protection strategies will be configured based on the model’s capabilities, with fewer restrictions compared to Fable 5.
In short, let's fully launch GPT-5.6, and we'll see the results through real-world testing～
Reference link:
[1]https://x.com/mark_k/status/2073467892889272609?s=20
[2]https://x.com/kimmonismus/status/2073799386535006210
[3]https://x.com/gippp69/status/2073697790723596469
This article is from the WeChat public account "Quantum Bit," authored by Lu Yu.