diff --git a/src/raglite/_config.py b/src/raglite/_config.py
index e178078..f217712 100644
--- a/src/raglite/_config.py
+++ b/src/raglite/_config.py
@@ -5,20 +5,31 @@
 
 import numpy as np
 import numpy.typing as npt
-from llama_cpp import Llama, LlamaRAMCache  # type: ignore[attr-defined]
+from llama_cpp import Llama, LlamaRAMCache, llama_supports_gpu_offload  # type: ignore[attr-defined]
 from sqlalchemy.engine import URL
 
 
 @lru_cache(maxsize=1)
 def default_llm() -> Llama:
     """Get default LLM."""
+    # Select the best available LLM for the given accelerator.
+    if llama_supports_gpu_offload():
+        # Llama-3.1-8B-instruct on GPU.
+        repo_id = "bartowski/Meta-Llama-3.1-8B-Instruct-GGUF"  # https://huggingface.co/meta-llama/Meta-Llama-3.1-8B-Instruct
+        filename = "*Q4_K_M.gguf"
+    else:
+        # Phi-3.1-mini-128k-instruct on CPU.
+        repo_id = "bartowski/Phi-3.1-mini-128k-instruct-GGUF"  # https://huggingface.co/microsoft/Phi-3-mini-128k-instruct
+        filename = "*Q4_K_M.gguf"
+    # Load the LLM.
     llm = Llama.from_pretrained(
-        repo_id="bartowski/Meta-Llama-3.1-8B-Instruct-GGUF",  # https://github.com/meta-llama/llama-models
-        filename="*Q4_K_M.gguf",
+        repo_id=repo_id,
+        filename=filename,
         n_ctx=8192,  # 0 = Use the model's context size (default is 512).
         n_gpu_layers=-1,  # -1 = Offload all layers to the GPU (default is 0).
         verbose=False,
     )
+    # Enable caching.
     llm.set_cache(LlamaRAMCache())
     return llm
 
@@ -26,9 +37,10 @@ def default_llm() -> Llama:
 @lru_cache(maxsize=1)
 def default_embedder() -> Llama:
     """Get default embedder."""
+    # Load the embedder.
     embedder = Llama.from_pretrained(
-        repo_id="ChristianAzinn/snowflake-arctic-embed-l-gguf",  # https://github.com/Snowflake-Labs/arctic-embed
-        filename="*f16.GGUF",
+        repo_id="yishan-wang/snowflake-arctic-embed-m-v1.5-Q8_0-GGUF",  # https://github.com/Snowflake-Labs/arctic-embed
+        filename="*q8_0.gguf",
         n_ctx=0,  # 0 = Use the model's context size (default is 512).
         n_gpu_layers=-1,  # -1 = Offload all layers to the GPU (default is 0).
         verbose=False,
diff --git a/tests/conftest.py b/tests/conftest.py
index 52a5d6d..c647d6a 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,7 +1,7 @@
 """Fixtures for the tests."""
 
 import pytest
-from llama_cpp import Llama, LlamaRAMCache  # type: ignore[attr-defined]
+from llama_cpp import Llama
 
 from raglite import RAGLiteConfig
 
@@ -9,15 +9,6 @@
 @pytest.fixture()
 def simple_config() -> RAGLiteConfig:
     """Create a lightweight in-memory config for testing."""
-    # Use a lightweight LLM.
-    llm = Llama.from_pretrained(
-        repo_id="bartowski/Phi-3.1-mini-4k-instruct-GGUF",  # https://huggingface.co/microsoft/Phi-3-mini-4k-instruct
-        filename="*Q4_K_M.gguf",
-        n_ctx=4096,  # 0 = Use the model's context size (default is 512).
-        n_gpu_layers=-1,  # -1 = Offload all layers to the GPU (default is 0).
-        verbose=False,
-    )
-    llm.set_cache(LlamaRAMCache())
     # Use a lightweight embedder.
     embedder = Llama.from_pretrained(
         repo_id="ChristianAzinn/snowflake-arctic-embed-xs-gguf",  # https://github.com/Snowflake-Labs/arctic-embed
@@ -30,5 +21,5 @@ def simple_config() -> RAGLiteConfig:
     # Use an in-memory SQLite database.
     db_url = "sqlite:///:memory:"
     # Create the config.
-    config = RAGLiteConfig(llm=llm, embedder=embedder, db_url=db_url)
+    config = RAGLiteConfig(embedder=embedder, db_url=db_url)
     return config