Verdict
Built from the measurements below
- Accuracy is too close to call: Nemotron 3 Ultra scored 60.0% and Step 5 Preview 63.8% on the same 80 questions, a gap within what chance alone could produce.
- Step 5 Preview is 1.2× cheaper per question as billed ($0.0047 vs $0.0057), reasoning tokens included.
- Nemotron 3 Ultra generates text 1.5× faster: 136 tokens per second against 93.
- Step 5 Preview starts answering sooner: 0.6 s to the first token, against 0.8 s for Nemotron 3 Ultra.
- Step 5 Preview accepts more context: 1M tokens against 262k.
Which should you choose?
Choose Nemotron 3 Ultra for faster streaming. Choose Step 5 Preview for the lower cost per correct answer ($0.0074 against $0.0094), a quicker first token and a 1M-token context window.
Accuracy gap -3.7 points (z = -0.49). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.