My iPad 3G makes the same noise. I also assumed it was the SIM card. I was going to test them out in the Apple Store, but its too noisy to hear any possible rattles in the floor models. Let me know if you find anything out.
If I hold mine in one hand and move it slightly, I can hear a rattling.I need to stay away from this forum cuz all of you are just crazy.
I shoke my 64gig 3G and yes I hear it too. But this type of rattling is
inperceptable from regular usage. But, if you hold it nest to your year
and place your ear near the backside apple logo and shake it violently yes
you will hear something.. must like how one of the posters described as
a grain knocking against something.. but only when you shake it violently
and put your ear up against it. And you can only recreate this sound if
you use both hands and shake rapidly since the ipad has a decent heft.
If you only hold it using one hand, you can't hear anything really. There is
also no physical cluncking that you can feel through your hands when you
shake it.
Thanks for all of the replies. Most of these reports of similar problems didn't come in until after last Friday, which was the last of my 14 day return period. Since the Apple store is a considerable distance from my house I went ahead and called AppleCare and just processed a full return. I am on vacation out of state this week and don't really have any time to mess with it. With these other reports of the same problem and the fact that I have had two in a row with this "issue" it seems like this is a commonality and just perhaps a design flaw. I am guessing it is just an antenna wire or something similar hitting the back of the case.
At this point with WWDC nearing I think I will wait to purchase another. There have been multiple reports of AT&T finally allowing tethering in iPhone OS 4.0. If this is the case I will just go ahead and buy the WiFi only model and tether as I won't be using cellular data very often. If I do end up with another 3G model that has the same "rattle" I will just be writing it off as "normal". Let me know if anyone finds anything else out.
I managed to get a hold of my mate's iPad and had a good play with it. It exhibits the same issue with the exact clicking/ticking/rattling noise internally. I have no idea where this sound comes from but it is surely there. I won't bother replacing it but Apple should at least be made aware of this issue.
funny, it seems as though all the people having this issue have the 3G model. i have the wifi modeling with no rattling at all