Hello,
There are many factors which cause the crackling sound on the Surface. Let's sort this out. However, to be able to understand the issue better, can you provide more details by answering these following questions:
• Can you tell us when and where did you purchase the device?
• Did you check if the crackling sound is recognizable with or without the power supply plugged in? Were there any differences?
• What troubleshooting steps have you tried so far?
Let us know so we can help you further.