Thanks for the input guys, I have sent an email to Gigabyte support (I'm using lots of r9 280x's) asking the question and will report back when/if they answer.

 I tend to agree with you all but it just seems strange if gravity is used in the calculations given there is liquid involved I might not be getting an even cooling effect across the entire chip.

 Hopefully we will hear from the Gigabye team. Thanks again

  Regards