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MPT-30B-Chat W8A8-GPTQ Quantized

This is an 8-bit weight, 8-bit activation (W8A8) GPTQ-quantized version of the original MPT-30B-Chat model from MosaicML. The model has been quantized using GPTQModel to reduce memory requirements while maintaining excellent performance.

MPT-30B-Chat is a chatbot-like model for dialogue generation. It was built by finetuning MPT-30B on the ShareGPT-Vicuna, Camel-AI, GPTeacher, Guanaco, Baize and some generated datasets.

License: CC-By-NC-SA-4.0 (non-commercial use only)

This model was trained by MosaicML and quantized by adamrb using GPTQModel.

Quantization Benefits

Balanced Performance: 8-bit quantization offers excellent quality with good memory savings
Better Quality: Higher precision than 4-bit while still reducing memory usage significantly
Stable Inference: More numerically stable than 4-bit quantization
Wide Compatibility: Works well across different hardware configurations

Quantization Details

Method: GPTQ (8-bit weights and activations)
Group Size: 128
Calibration Dataset: HuggingFaceH4/ultrachat_200k (20 samples)
Quantization Library: GPTQModel v2.2.0+
Supported Kernels: MarlinQuantLinear, TritonV2QuantLinear, TorchQuantLinear

Model Date

June 22, 2023 (Original), Quantized: July 2025

Model License

CC-By-NC-SA-4.0 (non-commercial use only)

Documentation

Blog post: Raising the bar for open-source foundation models
Codebase (mosaicml/llm-foundry repo)
GPTQModel Documentation
Questions: Feel free to contact us via the MosaicML Community Slack!

How to Use

With GPTQModel (Recommended)

python

from gptqmodel import GPTQModel

# Load the quantized model
model = GPTQModel.load(
    "adamrb/mpt-30b-chat-w8a8-gptq",
    device="cuda:0",
    trust_remote_code=True
)

# Generate text
result = model.generate("Hello, my name is")[0]
print(model.tokenizer.decode(result))

With Transformers + AutoGPTQ

python

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer, GPTQConfig

# Configure GPTQ for 8-bit
gptq_config = GPTQConfig(
    bits=8,
    group_size=128,
    desc_act=False
)

# Load model and tokenizer
model = AutoModelForCausalLM.from_pretrained(
    "adamrb/mpt-30b-chat-w8a8-gptq",
    device_map="auto",
    torch_dtype=torch.float16,
    quantization_config=gptq_config,
    trust_remote_code=True
)

tokenizer = AutoTokenizer.from_pretrained(
    "adamrb/mpt-30b-chat-w8a8-gptq",
    trust_remote_code=True
)

# Generate text
inputs = tokenizer("Hello, how can I help you today?", return_tensors="pt").to(model.device)
with torch.no_grad():
    outputs = model.generate(
        **inputs,
        max_new_tokens=100,
        do_sample=True,
        temperature=0.7,
        pad_token_id=tokenizer.eos_token_id
    )
print(tokenizer.decode(outputs[0], skip_special_tokens=True))

With vLLM (High Performance Inference)

python

from vllm import LLM, SamplingParams

# Initialize vLLM with GPTQ quantization
llm = LLM(
    model="adamrb/mpt-30b-chat-w8a8-gptq",
    quantization="gptq",
    dtype="float16",
    trust_remote_code=True,
    max_model_len=4096
)

# Set up sampling parameters
sampling_params = SamplingParams(
    temperature=0.7,
    top_p=0.9,
    max_tokens=100
)

# Generate text
prompts = ["Hello, my name is", "The future of AI is"]
outputs = llm.generate(prompts, sampling_params)

for output in outputs:
    print(f"Generated text: {output.outputs[0].text}")

Note: This model requires that trust_remote_code=True be passed to the loading methods. This is because we use a custom MPT model architecture.

Chat Template

This model uses a specific chat template. Here's how to format conversations:

python

from transformers import AutoTokenizer

tokenizer = AutoTokenizer.from_pretrained("adamrb/mpt-30b-chat-w8a8-gptq")

messages = [
    {"role": "user", "content": "What is the capital of France?"},
    {"role": "assistant", "content": "The capital of France is Paris."},
    {"role": "user", "content": "What is its population?"}
]

formatted_chat = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
print(formatted_chat)

Model Performance

Memory Usage Comparison

Model Version	Size	VRAM Usage (FP16)	VRAM Usage (BF16)
Original FP16	~58GB	~60GB	~58GB
W8A8 GPTQ	~30GB	~32GB	~30GB
W4A16 GPTQ	~15GB	~16GB	~15GB

Quality vs Efficiency Trade-off

W8A8: Better quality retention, moderate memory savings
W4A16: Maximum memory savings, slight quality trade-off

Hardware Requirements

Minimum VRAM: 32GB (for basic inference)
Recommended VRAM: 40GB+ (for optimal performance)
Supported GPUs: A6000, RTX 6000 Ada, A100, H100, etc.

Model Description

The architecture is a modification of a standard decoder-only transformer, now optimized with 8-bit quantization.

The model has been modified from a standard transformer in the following ways:

It uses FlashAttention
It uses ALiBi (Attention with Linear Biases) and does not use positional embeddings
It does not use biases
Quantized with GPTQ for 8-bit weights and activations

Hyperparameter	Value
n_parameters	29.95B
n_layers	48
n_heads	64
d_model	7168
vocab size	50432
sequence length	8192
quantization	8-bit weights and activations
group size	128

Quantization Configuration

json

{
    "bits": 8,
    "group_size": 128,
    "damp_percent": 0.1,
    "desc_act": false,
    "static_groups": false,
    "sym": true,
    "true_sequential": true,
    "model_name_or_path": null,
    "model_file_base_name": "model"
}

Training Data Mix

The original model was trained on the following data mix:

Data Source	Number of Tokens in Source	Proportion
Airoboros/GPT4-1.2	26.4M	1.71%
Baize	55.0M	3.57%
Camel	301M	19.54%
GPTeacher	7.56M	0.49%
Guanaco	15.6M	1.02%
LongCoversations	18.4M	1.19%
ShareGPT	821M	53.24%
WizardLM	297M	19.23%

Use Cases

When to Choose W8A8 over W4A16:

Quality Priority: When you need the best possible quality retention
Moderate Memory Constraints: When you have sufficient VRAM but want some memory savings
Stable Inference: When numerical stability is important for your application
Production Deployment: When you need a balance of efficiency and reliability

When to Choose W4A16 instead:

Extreme Memory Constraints: When VRAM is very limited
Maximum Throughput: When you need to serve many concurrent requests
Edge Deployment: When running on resource-constrained hardware

Limitations and Biases

The following language is modified from EleutherAI's GPT-NeoX-20B

MPT-30B-Chat can produce factually incorrect output, and should not be relied on to produce factually accurate information. MPT-30B-Chat was trained on various public datasets. While great efforts have been taken to clean the pretraining data, it is possible that this model could generate lewd, biased or otherwise offensive outputs.

Additional Quantization Considerations:

8-bit quantization provides better numerical stability than 4-bit
Quality retention is excellent compared to the original model
Performance may vary across different hardware configurations

Troubleshooting

Common Issues

CUDA Out of Memory: This model requires more VRAM than the 4-bit version
Slow Inference: Ensure you're using the appropriate quantization backend for your hardware
Quality Issues: Try different sampling parameters (temperature, top_p, top_k)

Performance Tips

Use torch.compile() for faster inference on compatible PyTorch versions
Enable FlashAttention with attn_impl='triton' for better memory efficiency
Use mixed precision (fp16/bf16) for optimal performance

Acknowledgements

This model was finetuned by Sam Havens and the MosaicML NLP team. GPTQ quantization by adamrb using GPTQModel.

Disclaimer

The license on this model does not constitute legal advice. We are not responsible for the actions of third parties who use this model. Please consult an attorney before using this model for commercial purposes.

Citation

Please cite this model using the following format:

@online{MosaicML2023Introducing,
    author = {MosaicML NLP Team},
    title = {Introducing MPT-30B: Raising the bar for open-source foundation models},
    year = {2023},
    url = {www.mosaicml.com/blog/mpt-30b},
    note = {Accessed: 2023-06-22},
    urldate = {2023-06-22}
}

For the quantization method, please also cite:

@article{frantar-gptq,
    title={{GPTQ}: Accurate Post-training Compression for Generative Pretrained Transformers}, 
    author={Elias Frantar and Saleh Ashkboos and Torsten Hoefler and Dan Alistarh},
    journal={arXiv preprint arXiv:2210.17323},
    year={2022}
}