I had the same whine in my S2000. It was 100% RPM dependent. I took it to a number of honda dealerships and all said it was normal. I didnt belive them untill I went on an S2000 cruise and found most other S2000's made the same noise. it sounded almost like an alternator whine of some sorts. Anyways I drove the car around for a year with this noise and I had no issues. towards the end my brain just learned to tune it out of my hearing ! lol I had my S2000 for 1.5 years and the one thing I learned about that car is it makes a lot of unexplained noises ! everything from the engine to the gear box to the diff. It was just a noisy car and most of the noise was normal (due to no sound proofing ) Anyways back to driving a euro again now and its like driving a car with ear plugs on compared to the S2000. Its dead quite !