Spark-X2.5-1.7B-mlx-4bit

4-bit MLX conversion of XHToken/Spark-X2.5-1.7B optimized for Apple Silicon native GPU inference.

Converted by: SirSahOl
Source Model: XHToken/Spark-X2.5-1.7B
Framework: MLX by Apple
Quantization: 4-bit (Average 4.50 bits per weight)
Format: safetensors
License: apache-2.0

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Model Details

• Architecture: Spark2_5ForCausalLM
• Parameters: 1.7B
• Context Length: 1,048,576 tokens
• Format: MLX (Apple Silicon native GPU format)
• Quantization: 4-bit (Average 4.50 bits per weight)
• Active VRAM Footprint: ~1.3 GB (Minimum recommended: 8 GB Unified Memory)

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Quick Start

Installation

pip install mlx-lm

Usage

CLI

# Chat interactively
mlx_lm.chat --model SirSahOl/Spark-X2.5-1.7B-chat-mlx-4bit

# Generate text
mlx_lm.generate --model SirSahOl/Spark-X2.5-1.7B-chat-mlx-4bit --prompt "Write a short poem about artificial intelligence."

Python API (with Chat Template)

from mlx_lm import load, generate

model, tokenizer = load("SirSahOl/Spark-X2.5-1.7B-chat-mlx-4bit")

messages = [
    {"role": "user", "content": "Explain quantum superposition in simple terms."}
]
prompt = tokenizer.apply_chat_template(
    messages, tokenize=False, add_generation_prompt=True
)

response = generate(model, tokenizer, prompt=prompt, verbose=True)
print(response)

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Performance Benchmarks

Measured Benchmarks (Apple M1)

Benchmarked on Apple M1 with 8GB unified memory. Average over 5 runs with 256 max tokens.

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Multi-Quantization Comparison

Evaluate your hardware budget and choose the optimal precision:

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Who Should Use This?

General guidance:

• Use 4-bit if you want to run this model alongside IDEs, browsers, and background development tools.
• Use 8-bit if you have 16GB+ unified memory and require superior reasoning and code accuracy.
• Use 16-bit for research, benchmarking, evaluation, or high-end workstation deployments.

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Other Quantization Variants

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LM Studio & Local Inference Setup Guide

To prevent runaway loops and ensure correct conversational turn-taking, configure custom stop tokens in your local inference runtime:

1. <|im_start|>
2. <|im_end|>
3. <|endoftext|>

Prompt Template Formatting

• System Prefix: <|im_start|>system\n
• System Suffix: <|im_end|>\n
• User Prefix: <|im_start|>user\n
• Assistant Suffix: <|im_end|>\n<|im_start|>assistant\n

Ollama Quickstart

FROM SirSahOl/Spark-X2.5-1.7B-chat-mlx-4bit
PARAMETER stop "<|im_start|>"
PARAMETER stop "<|im_end|>"
PARAMETER stop "<|endoftext|>"
PARAMETER temperature 0.7

ollama create spark-x2.5-1.7b-chat-mlx-4bit -f Modelfile
ollama run spark-x2.5-1.7b-chat-mlx-4bit

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Conversion Details

Reproduction

To reproduce this conversion:

pip install mlx-lm==0.31.3
python3 -m mlx_lm.convert --hf-path XHToken/Spark-X2.5-1.7B --mlx-path output/Spark-X2.5-1.7B-mlx-4bit -q --q-bits 4

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Limitations & Known Issues

• 4-bit group-wise quantization introduces minor precision loss compared to unquantized weights; for deep mathematical derivations or precision-critical reasoning, test the 8-bit or 16-bit variants.
• High context sequences (>32K tokens) require sufficient unified memory headroom; ensure unified memory is not overcommitted.
• This is a weight-only MLX conversion designed specifically for Apple Silicon GPUs (M1/M2/M3/M4 series).

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License

This model conversion inherits the license of the source model: apache-2.0.

See the original model card for full license details.

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Changelog

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Converted with MLX Foundry — a professional pipeline for converting models to Apple MLX format.