White Noise in Rendering

[Benrubinstein11]

Hi All, I am wondering if you can help me with an issue I have been seeing in majority of my interior rendering scenes. In this rendering I am working on a jewelry store that has a lot of glass showcases throughout. The main issue is the white noise that shows up in the rendering. I have tried a multitude of different ways to try to get rid of this, including turning global illumination on/off, increasing material samples of lights, increasing material samples of the black material on the showcase, trying both black paint and black plastic as material for showcase, rendering using a large number of samples, making the showcase material less black. Basically I have looked through this forum for this issue and have tried everything I have seen suggested.

In the attached rendering i did a region render at 200 samples.
My Lighting Settings are:
Shadow Quality: 3
Ground Illumination: Checked
Self Shadows: Not Checked
Ray Bounces: 24
Global Illumination: Checked
Global Illumination Bounces: 24
Caustics: Check
Interior Mode

Materials:
Area Light White
Hard Rough Plastic Black
Glass Window Generic Grey
Aluminum Rough

Pretty much all of the light is coming from ceiling lights located throughout the room. I have tried turning the light wattage down but am still getting the same result.There are also lights inside of the showcase in the corners. Let me know if you guys have any suggestions to improve this.

Thanks in advance!

[KeyShot]

I have sent you a pm.