Faulty 520HX Fan?

Hi. Since I bought this PSU my CPU temp has risen over 10 degrees C. After RMAing the CPU and motherboard, and still no change, I have come to the conclusion that it is the PSU. Changing the PSU brings down the cpu temp again.

My PSU sits above the CPU and I have noticed that the psu fan is running very very slowly. I woud say around 150rpm after comparing it with other fans. I can actually read the Corsair logo on the centre of the fan whilst it is running. Running dual prime does not increase the psu fan speed.

I suspect the fan is faulty?

Our design does run the fan very slow. However, if you believe it to be defective, we'll replace the PSU.