Will PCI Express 2.0 X16 fit into the same slot as PCI Express X16?

I a newbie.

I have a MB that says it's for PCI Express x16. I'm having a hard time
finding a really QUIET one for just x16. There are a whole bunch for PCI
Express 2 x16. I was wondering if the new ones will fit in the same slot as
the old one and just run at a slower speed? I don't mind if it does run at
a slower speed.

"pvong" <vonger@*dot*com> wrote in message
news:OYIw%(E-Mail Removed)...
>I a newbie.
>
> I have a MB that says it's for PCI Express x16. I'm having a hard time
> finding a really QUIET one for just x16. There are a whole bunch for PCI
> Express 2 x16. I was wondering if the new ones will fit in the same slot
> as the old one and just run at a slower speed? I don't mind if it does
> run at a slower speed.

I'd be very surprised if you couldn't find the answer to this on wikipedia.
Newbies need to know how to search for easy answers too. Answers there will
be much more detailed.