E6420: Strange Electronic Buzzing Sound

Hello everyone. I had the keyboard and LCD back cover replaced on my E6420 under my Complete Care agreement, but I notice a strange (new) issue now.

Since the repair, there is an audible "buzzing" sound. I'm not sure how to describe it. I'm not sure what can make that type of noise. Even when I put an SSD in it (which as you know has no moving parts) I still hear it. I hear it whenever I scroll a window up or down, as well as whenever the hard drive has activity. I can reproduce this sound 100% of the time by just scrolling contents in a window up or down. I hear it even with the speakers muted. This sound was not present prior to the repair.

Any ideas what can make this type of noise? It's almost like some sort of static interference or internal computer sound that is amplified somehow. I opened the bottom cover and checked underneath the keyboard for loose wires but I didn't find any. The sound does not go along with the fan or any predictable pattern other than hard drive activity and/or scrolling windows up and down with either the trackpad or external USB mouse.

Update: I removed the hard drive and booted with a Linux LiveCD. I still hear the buzzing sound, even without the hard drive.

 

Sorry to keep bugging you guys, but has anyone had this happen?

I had Dell replace the lid and the heat sink but after I did the repair, the problem is still happening.

The sound starts under the keyboard around the CPU, and travels to the right speaker.

 

Well, once with my PC any fast motion on the screen had a whine from the PC tower. It was either capacitor whine or coil whine from my nVidia video card. I noticed it when the cover was off my PC. I ended up switching to a new video card. The best way to test for something like that is to play a video and not be interactive with the computer. Play something that's fast motion and don't touch any input device and see if you can still hear it.

 

I still hear it even with a fast paced movie playing.

 

Well it's like I said. You say you can reproduce when the screen contents move up and down, and you can reproduce with a fast paced movie. Maybe it's your video card or some video component. When the screen doesn't change do you hear the sound?

 

I don't normally hear the sound when the screen changes, but it also makes the sound any time there's HDD activity. It can sound like a normal spinning hard drive grinding away, even though it's an SSD and the sound is not coming from the SSD.

Dell called me this morning, they are replacing this unit. I think this is a good solution. I'll post back when I get the new one, but that will probably solve it so I'll mark this solved.

Thank you!