Muse Spark Open 816B A42B vs Step 5 Preview

Step 5 Preview leads llmrun Score 128.0 to 125.6 (ranges overlap); neither fits 24 GB.

Model A · Meta

Muse Spark Open 816B A42B

125.6llmrun Score

822.0B · 42B active · Other · Sep 2026

Vision

Model B · StepFun

Step 5 Preview

128.0llmrun Score

604.3B · 27B active · 1M context · Other · Sep 2026

ChatFunctions

Which should you choose?

Choose Muse Spark Open 816B A42B if you want…

Also does vision
Step 5 Preview doesn't list it

Choose Step 5 Preview if you want…

Higher llmrun Score
128.0 vs 125.6, ranges overlap
Stronger at science
134.2 vs 125.3
Lighter on memory
398.9 vs 542.5 GB at Q4_K_M
Also does chat, function-calling
Muse Spark Open 816B A42B doesn't list it

On your hardware

Each model at its default quant (Q4_K_M), a smaller one when it must. Estimates, ±20%.

MemoryMuse Spark Open 816B A42BStep 5 Preview

8 GB

RTX 4060 · 8 GB tier

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

12 GB

RTX 3060 12GB · 12 GB tier

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

16 GB

RTX 5060 Ti 16GB · 16 GB tier

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

24 GBreference

RTX 4090 · 24 GB tier

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

32 GB

RTX 5090 · 32 GB tier

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

48 GB

RTX A6000 · 48 GB tier

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

Mac 32 GB

Mac Mini M4 · Macs

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

Mac 64 GB

Mac Studio M4 Max · Macs

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

Mac 128 GB

Mac Studio M4 Max · Macs

Muse Spark Open 816B A42B

Doesn't fit

smallest quant needs 258.1 GB

Step 5 Preview

Doesn't fit

smallest quant needs 191.4 GB

Reference GPU: RTX 4090. Tinted cell = the better pick on that machine (fits, more headroom, or at least 10% faster).

llmrun Score

with its 90% range · bars share one scale

Muse Spark Open 816B A42B Step 5 Preview

Overall

Muse Spark Open 816B A42B

125.6123–128

Step 5 Preview

128.0124–132

Coding

Muse Spark Open 816B A42B

127.9120–135

Step 5 Preview

no data

Agents

Muse Spark Open 816B A42B

113.8105–123

Step 5 Preview

no data

Math

Muse Spark Open 816B A42B

128.4125–132

Step 5 Preview

no data

Science

Muse Spark Open 816B A42B

125.3113–138

Step 5 Preview

134.2122–147

Muse Spark Open 816B A42B · #10 of 101 open models · #8 of 98 that fit ≤640 GB

Step 5 Preview · #8 of 101 open models · #6 of 98 that fit ≤512 GB

Benchmarks

2 shared boards: Muse Spark Open 816B A42B leads 0, Step 5 Preview leads 2 · Benchmarks imported Oct 2026

BoardMuse Spark Open 816B A42BStep 5 Preview

SciCode

Muse Spark Open 816B A42B

58.5%#5/68 open

Lab-reportedEpoch AI · Oct 2026

Step 5 Preview

58.9%#4/68 open

Lab-reportedEpoch AI · Sep 2026

CritPt

Muse Spark Open 816B A42B

14.9%#9/68 open

Lab-reportedEpoch AI · Oct 2026

Step 5 Preview

20.9%#3/68 open

Lab-reportedEpoch AI · Sep 2026

16 more boards (other shared and single-model boards)

Only Muse Spark Open 816B A42B (15)

Only Step 5 Preview (1)

ProofBench42.0%

VRAM by quantization

Memory to load the model and 2K context; below it, the total at 32K and 128K context. Lighter side in bold.

QuantMuse Spark Open 816B A42BStep 5 Preview

Q2_K

Muse Spark Open 816B A42B

384 GB304.1 GB file

32K 404 GB · 128K 469 GB

Step 5 Preview

283 GB182.5 GB file

32K 301 GB · 128K 360 GB

Q3_K_M

Muse Spark Open 816B A42B

441 GB~400.7 GB file

32K 461 GB · 128K 525 GB

Step 5 Preview

324 GB~294.6 GB file

32K 343 GB · 128K 402 GB

Q4_0

Muse Spark Open 816B A42B

452 GB466.3 GB file

32K 472 GB · 128K 537 GB

Step 5 Preview

not listed

Q4_K_M

Muse Spark Open 816B A42B

543 GB~493.2 GB file

32K 563 GB · 128K 627 GB

Step 5 Preview

399 GB~362.6 GB file

32K 417 GB · 128K 476 GB

Q5_K_M

Muse Spark Open 816B A42B

644 GB~585.7 GB file

32K 664 GB · 128K 729 GB

Step 5 Preview

474 GB~430.6 GB file

32K 492 GB · 128K 551 GB

Q6_K

Muse Spark Open 816B A42B

746 GB~678.2 GB file

32K 766 GB · 128K 831 GB

Step 5 Preview

548 GB~498.6 GB file

32K 567 GB · 128K 626 GB

Q8_0

Muse Spark Open 816B A42B

904 GB871.6 GB file

32K 924 GB · 128K 989 GB

Step 5 Preview

665 GB~604.3 GB file

32K 683 GB · 128K 742 GB

6 more quants

IQ2_XXS

Muse Spark Open 816B A42B

249 GB225.6 GB file

32K 269 GB · 128K 333 GB

Step 5 Preview

183 GB~166.2 GB file

32K 201 GB · 128K 260 GB

IQ2_S

Muse Spark Open 816B A42B

283 GB275.5 GB file

32K 303 GB · 128K 367 GB

Step 5 Preview

not listed

IQ3_XXS

Muse Spark Open 816B A42B

350 GB340.4 GB file

32K 371 GB · 128K 435 GB

Step 5 Preview

not listed

IQ3_M

Muse Spark Open 816B A42B

not listed

Step 5 Preview

299 GB271.6 GB file

32K 318 GB · 128K 377 GB

Q4_K_S

Muse Spark Open 816B A42B

509 GB470.1 GB file

32K 529 GB · 128K 593 GB

Step 5 Preview

not listed

BF16

Muse Spark Open 816B A42B

1808 GB1640.3 GB file

32K 1829 GB · 128K 1893 GB

Step 5 Preview

1330 GB~1208.7 GB file

32K 1348 GB · 128K 1407 GB

How to run each

Muse Spark Open 816B A42B

Ollama · Q4_K_M

$ollama run hf.co/Interchained/Muse-Spark-Open-816B-A42B-GGUF:Q4_K_M

All ways to run Muse Spark Open 816B A42B →

Step 5 Preview

Ollama · Q4_K_M

$ollama run hf.co/smalinin/Step-5-Preview-GGUF

All ways to run Step 5 Preview →

Specifications

Specifications of Muse Spark Open 816B A42B and Step 5 Preview
Spec	Muse Spark Open 816B A42B	Step 5 Preview
Publisher	Meta	StepFun
Parameters	822.0B	604.3B
Active parameters	42B per token	27B per token
Architecture	—	Step5ForConditionalGeneration
Context	—	1M tokens
Modalities	Vision	Chat, Function-calling
License	Other	Other
Released	Sep 2026	Sep 2026

Frequently Asked Questions

Which is better, Muse Spark Open 816B A42B or Step 5 Preview?

Step 5 Preview leads llmrun Score 128.0 to 125.6 (ranges overlap); neither fits 24 GB. Choose Muse Spark Open 816B A42B for also does vision; choose Step 5 Preview for higher llmrun Score and stronger at science.

Which needs less VRAM, Muse Spark Open 816B A42B or Step 5 Preview?

At Q4_K_M, Muse Spark Open 816B A42B requires 542.5 GB while Step 5 Preview needs 398.9 GB, making Step 5 Preview the easier model to run on your local setup.

Can I run Muse Spark Open 816B A42B or Step 5 Preview on a 16 GB GPU?

Muse Spark Open 816B A42B does not fit (smallest quant needs 258.1 GB); Step 5 Preview does not fit (smallest quant needs 191.4 GB).