Let's play the game of "what the heck is wrong with my Boxster now?"

[batshapedheart]

Here's a video clip with the sound it just started making at start up.
Any input appreciated

http://youtu.be/Nmy_UD6xU90

[particlewave]

You have either got something stuck in your engine compartment fan, it's failing, or the SAI pump.

[san rensho]

Its the SAI pump. Theres a fix if you search on renlist which involves removing the pump, taking it apart and greasing the bearings in the pump. Easy fix. The pump is pretty pricey.

[Jamesp]

You'll need to fix the existing pump soon or you'll fry the bearing and have to replace the pump.

[jsceash]

Your running a circular saw in you other hand. if not,
I'm going to agree with the others your air pump is biting it.

[kk2002s]

I had a less severe whine from SAP
Pulled it opened up got to bearing
Use a basic hand grease gun with a needle adaptor to get grease behind the seals
It another sealed bearing that losses it's grease. Sound familiar

[Gelbster]

If you examine the pump bearing carefully ,it should have a generic part number on it.It is usually 4 digits followed by letters. You can then search for a similarly dimensioned bearing or even upgrade to a higher temperature rated bearing. According to this link you can get a 1/4" Timken replacement inexpensively:
http://www.audiworld.com/forums/a6-s6-c5-platform-discussion-7/writeup-2-7t-secondary-air-injection-sai-pump-rebuild-1727056/
If you remove the bearing and take it to your local bearing store, you may even be able to get a ceramic bearing replacement. You just need i.d.,o.d. and width.Then decide what type of seals 7 grease you want. The bearings come in various grades(ABEC is common) but for this low stress application ,the utility grade is probably adequate.
Please let us know what you find and what you do to repair the pump.