What is this noise, coming from left side of engine
 

http://www.youtube.com/watch?v=BXD0i-uJaAE This is a recorded video, you can hear the noise quite well, any ideas? PS pump was changed, and the belt. It's not a pulley either, they were checked.

Are you sure it is the left side. Waterpumps are known for going back and will cause noises like such. Sometimes they sound like they are coming from the top of the motor.

Just had it at my buddies shop, it's coming from the valve cover on the left side, definetely not the top of the motor though. Any ideas? never looked at the cyl. head of a boxster, so not sure what components could be acting up in there.

Retorque the spark plugs and hope that one of them has backed out. They are known to do that if not torqued properly and make a chirping sound.

Will this get louder when revved? Is it a good chance this is the issue?

Quite possibly. It takes all of about 30 minutes to retorque them, so get in there and check them.

So it's not the sparkplugs, and just to be sure I ran the engine without the serpentine belt, and it's still making the noise. When the engien is running, I took the oil fill cap off, and it idled down and got a lot louder, what do you think that means guys? Thanks for the input so far.

The OAS can also make a chirping sound when it goes bad and the internal diaphragm tears. It would make noise to the passenger rear of the motor though.

Actually just changed the OAS today finally, it was doing it before and still is, it's definetely a left side noise.