diff --git a/engines/hf/runner.py b/engines/hf/runner.py
index 427de4e..d260e0e 100644
--- a/engines/hf/runner.py
+++ b/engines/hf/runner.py
@@ -10,6 +10,8 @@
 from termcolor import cprint
 from transformers import AutoModel, AutoProcessor, AutoTokenizer
 
+from mineru_diffusion.utils.runtime import maybe_disable_flash_attention, resolve_torch_dtype
+
 
 STOP_STRINGS = ("<|endoftext|>", "<|im_end|>")
 SYSTEM_PROMPT = "You are a helpful assistant."
@@ -70,7 +72,21 @@ def run(args: argparse.Namespace) -> None:
     prompt = args.prompt or TASK_PROMPTS[args.prompt_type]
     model_path = Path(args.model_path).resolve()
     device = args.device
-    dtype = getattr(torch, args.dtype)
+    flash_attn_disabled = maybe_disable_flash_attention(device)
+    dtype, resolved_dtype_name = resolve_torch_dtype(device, args.dtype)
+
+    if flash_attn_disabled:
+        cprint(
+            "FlashAttention disabled for this GPU; using PyTorch SDPA fallback.",
+            color="yellow",
+            flush=True,
+        )
+    if resolved_dtype_name != args.dtype:
+        cprint(
+            f"CUDA device does not support {args.dtype}; falling back to {resolved_dtype_name}.",
+            color="yellow",
+            flush=True,
+        )
 
     _print_summary(args, model_path, device, dtype)
 
diff --git a/mineru_diffusion/utils/runtime.py b/mineru_diffusion/utils/runtime.py
new file mode 100644
index 0000000..b183f9a
--- /dev/null
+++ b/mineru_diffusion/utils/runtime.py
@@ -0,0 +1,56 @@
+import os
+
+import torch
+
+
+def _parse_device(device: str) -> torch.device | None:
+    try:
+        return torch.device(device)
+    except (RuntimeError, TypeError, ValueError):
+        return None
+
+
+def should_disable_flash_attention(device: str) -> bool:
+    if os.environ.get("MINERU_DISABLE_FLASH_ATTN") == "1":
+        return True
+
+    torch_device = _parse_device(device)
+    if torch_device is None or torch_device.type != "cuda" or not torch.cuda.is_available():
+        return False
+
+    try:
+        major, _ = torch.cuda.get_device_capability(torch_device)
+    except Exception:
+        return False
+    return major < 8
+
+
+def maybe_disable_flash_attention(device: str) -> bool:
+    if not should_disable_flash_attention(device):
+        return False
+
+    os.environ["MINERU_DISABLE_FLASH_ATTN"] = "1"
+
+    try:
+        import flash_attn
+    except ImportError:
+        return True
+
+    flash_attn.flash_attn_func = None
+    return True
+
+
+def resolve_torch_dtype(device: str, requested_dtype: str) -> tuple[torch.dtype, str]:
+    torch_device = _parse_device(device)
+    resolved_dtype = requested_dtype
+
+    if (
+        requested_dtype == "bfloat16"
+        and torch_device is not None
+        and torch_device.type == "cuda"
+        and torch.cuda.is_available()
+        and not torch.cuda.is_bf16_supported()
+    ):
+        resolved_dtype = "float16"
+
+    return getattr(torch, resolved_dtype), resolved_dtype
diff --git a/scripts/run_end2end.py b/scripts/run_end2end.py
index af67b6c..9ac2baf 100644
--- a/scripts/run_end2end.py
+++ b/scripts/run_end2end.py
@@ -21,6 +21,7 @@
     sys.path.insert(0, str(REPO_DIR))
 
 from mineru_diffusion.utils.bbox import draw_bbox
+from mineru_diffusion.utils.runtime import maybe_disable_flash_attention, resolve_torch_dtype
 
 
 STOP_STRINGS = ("<|endoftext|>", "<|im_end|>")
@@ -369,13 +370,25 @@ def __init__(
     ) -> None:
         self.model_path = model_path
         self.device = device
-        self.torch_dtype = getattr(torch, dtype)
+        flash_attn_disabled = maybe_disable_flash_attention(device)
+        self.torch_dtype, resolved_dtype_name = resolve_torch_dtype(device, dtype)
         self.max_length = max_length
         self.block_size = block_size
         self.temperature = temperature
         self.remask_strategy = remask_strategy
         self.dynamic_threshold = dynamic_threshold
 
+        if flash_attn_disabled:
+            print(
+                "FlashAttention disabled for this GPU; using PyTorch SDPA fallback.",
+                file=sys.stderr,
+            )
+        if resolved_dtype_name != dtype:
+            print(
+                f"CUDA device does not support {dtype}; falling back to {resolved_dtype_name}.",
+                file=sys.stderr,
+            )
+
         self.tokenizer = AutoTokenizer.from_pretrained(model_path, trust_remote_code=True)
         self.processor = AutoProcessor.from_pretrained(model_path, trust_remote_code=True, use_fast=False)
         self.model = AutoModel.from_pretrained(