All sorted!! I didn't realise I could install the optical drive back over the new hard drive, the fan keeps both very cool. Once I connected the optical drive & thermal sensor the fans calmed down to 1100 rpm. If you don't want to install the optical drive just take off the thermal sensor and connect it to the new hard drive and the logic board. Another thing I have learned in this experience is you need the optical drive in to install Windows (bootcamp) or you get a partitioning error at install. It is a safety feature Apple incorporated. Hope this helps others!! Thanks again for the replies
Hi, I have successfully installed a 1TB Seagate Hybrid hard drive and everything seems fine, except the fans are blowing at full speed constantly. Is this because the heat sensor for the optical drive is missing now? Has anyone got a solution?