STREAK65/STREAK65 LP may display buzzing/coil whine caused due to the PWM (Pulse-width modulation) which is how the LEDs within the keyboard power and adjust their brightness levels. The dimmer the LED is, the less you'll hear it and vice versa.
Most MCU's in modern electronic devices use PWM to control the brightness of the LEDs, which is why it is also noticeable on other keyboards or even mice that use RGB LED lights as well.
The main reason some keyboards may not have this as obvious comes down to their material. For example, a keyboard with a larger aluminium case is filled with extra sound dampening foam or other insulating material that may absorb the buzz more efficiently within the case.
You can use the following video for clarification:
And a good example of the video with the buzz/whine sound can be seen through here:
Our STREAK65/STREAK65 LP have a thinner case, so the buzzing will be more obvious if you raise the colour levels on it.