**UPDATE**
I opened up my side panel and it is the pump making the high pitched buzzing/whirring sound. I have the EK-XRES 140 with D5 pump (pump/res combo) there is definitely enough water and it is gravity fed so I'm not sure what the issue is. It is a molex and pwm controlled pump so this noise only occurs under loads. (It is plugged into one of the fan headers on the mobo and the molex into the PSU)
I opened up my side panel and it is the pump making the high pitched buzzing/whirring sound. I have the EK-XRES 140 with D5 pump (pump/res combo) there is definitely enough water and it is gravity fed so I'm not sure what the issue is. It is a molex and pwm controlled pump so this noise only occurs under loads. (It is plugged into one of the fan headers on the mobo and the molex into the PSU)