I recently bought a Fractal Design Define R5 case. I installed 3 Fractal Design silent fans, the X2 GP-14, 2 in front and one in the back. My cpu fan as you see is the V8 GTS with two fans. I ran all the fan tuning software from ASUS (AI Suite 3) it calibrated the fan just fine but at around 400 rpm till over 1000 rpm, the fans are making a high pitch noise that grows as rpm rise up. The setup is absolutely silent and this hiss is totally annoying. Before starting thinking of other cooling solutions, can you help me with this issue? Is it a fan problem? An inside the box air-flow issue? The box fans are connected to the case's fan speed control, I set them to silent, medium and high in case there's something wrong with the air flow that creates this problem with the cpu fans but that's not the case. I really love the design of the V8, it's like a jewel on my rig, but this noise is intolerable. Thanks for your time!