In a large skillet, bring about 1/4-inch water to boil. Add cauliflower, cover with a lid, and steam until tender about 4 minutes. Drain and cool while you prep other ingredients.
In a large skillet over medium heat, cook bacon until crispy, about 3 minutes per side. Transfer to a paper towel-lined plate to drain. Chop when cool.
In a large bowl, whisk together sour cream, mayonnaise, lemon juice, and garlic powder. Add cauliflower and toss gently; season with salt and pepper. Fold in bacon, cheddar cheese, and chives. Serve warm or cold.