The boot screen was wrong. The familiar glowing Windows logo was there, but the four colored petals didn’t form a flag. They pulsed in a slow, breathing rhythm. Below it, in a crisp sans-serif that wasn’t Segoe: Windows 7 SP3 — The Last Good One.
Stop looking for Service Pack 3. It does not exist. Your target is Service Pack 1 + KB3125574 . windows 7 service pack 3 download 64-bit offline iso
Here is a deep feature on what you actually need, how to get the closest equivalent to an "SP3," and the risks involved in searching for it. The boot screen was wrong