I have an old Volvo that I recently put a new fan clutch on. I switched to the "heavy duty" version of the clutch, but I think what I'm about to tell you is something to consider.
The old fan clutch seemed to work fine and also had plenty of drag, but I was replacing all of the cooling system parts so I went ahead with it.
When the car has been idling in traffic on a warm day at a stop light, the sound that the fan makes as I take off is very very noticeable. The fan is exactly the same, the only difference is the clutch. It sounds like a truck. It moves that much more air.
If your vehicle is hot and you can't hear the fan really moving the air when you rev it (more air movement than when it was cool), then maybe the clutch is toast or it's not getting hot enough to activate. My fan clutch needs to get pretty hot. I don't have a temp gauge with degrees on it (it's factory), but it needs to really get warm before it really wakes up.
Once up to a decent speed the fan quiets down on my Volvo - and I believe that exactly how it was designed to work. Driving gives enough airflow through the radiator that the clutch cools off (along with the coolant) and the clutch becomes free wheeling (or closer to it).
Is your radiator getting as hot as the engine itself? Can you get a BBQ temp probe into the fins to see what it is reading? The coolant on the hot side of your radiator really should be close to what it's running at near the temp sender in the engine. If the radiator isn't getting hot that's a big problem.
I hope you find the issue, best of luck.