Bubbles!

I have a brand new H115i that I seem to be having issues with bubbles. I believe it is air in the coolant.

The pump will intermittently make a light tone rattle sound that sounds underwater. It's very annoying and in quiet mode can be heard across a quiet room. It happens five minutes or so and can last for a few minutes. It seems worse after the pump has been run aggressively, taking ten to fifteen minutes to settle down again afterwards. After time it reduces, but never fully goes away, there is nearly always a slight rattle noise from the pump.

Firstly, is this acceptable for a brand new cooler? Or should it be replaced? I can get a replacement within 24 hours. Should I do that? Is rattle enough concern for a return?

The top of the radiator is higher than the pump ( good thing ), so air tends towards the top of the radiator. However, the pipes are at the top of the radiator so air is tending to head for the pipes ( bad thing ).

I am not sure how practical it would be to turn the radiator upside down to trap the air at the top of the radiator in what would be the opposite end to the pipes. I think this may well solve the problem but it may also cause other problems, specifically that the pipes will barely reach and will have issues with the graphics card! Top mounting the radiator is possible but it completely messes up the balance of the ventilation of the case. I have a graphics card that vents in to the case so it's like placing a fire under the radiator if its at the top. I have heard mixed opinions on that, which is why the radiator is currently at the front. Changing the graphics card is out of the question at the moment.

Any thoughts?

OK I found a video on youtube that has the same noise. This is the rattle ...

[ame]

It's definitely the same noise.

When the air bubbles passed through the pump earlier the noise got much, much louder.