I have some water cooled 8800GTX cards (BFG branded) that whine. When under stress the capacitors start to squeal. Nothing can be done except to replace the capacitors which would be a lot of hard work and definitely void your warranty.
If it's really more of a hissing than a whine then I suppose it could be the fan. You could try forcing a speed change with Rivatuner to see if there's a change.
A bus station is where a bus stops. A train station is where a train stops. On my desk, I have a work station…