My first though was like Khuon's that this is a Cannondale. After looking at the close-ups, I'm almost certain.

My room-mate in college had nearly an identical bike but without the suspension fork. I'm guessing late 80's or early 90's vintage. I graduated in '93, and at that point, his frame was a good 4 to 5 years old.

His was painted, and stipped to raw aluminum. Looks like this was done to this frame as well.

Send Cannondale an e-mail and see if the serial number matches up with any of their fabrication numbers.

L8R