IMac :: 27" IMac Seagate 1Tb HDD Noise Normal?

rite as some will already know i have took back my 27" iMac a total of 6 times and now i am on my 7th (4th one had screen issues), after actually accepting the "belly rumbling" "popping" noise and just getting on with the i5 experience, i thought i would actually contact Seagate direct on the actual matter for the rest of people on here who have doubt about there seagate hard drives.So i ring the operator i told him the whole story his first reply was sorry we dont support apple hardware! my response was "respected but the hard drive used is a seagate product"! he then replied saying sorry sir i misunderstood and quickly responded how can i help. I then repeated the problem and he asked for the HDD serial number, i was then very specific on the the noises we are all hearing and he made me repeat what i said a good 3 times so he had a very good understanding (in other words he did take this all seriously) he then said he was going to talk to the relevant person and put me on hold....10 minutes later he's back on the phone and he again asked me a final time! (ffs) to explain the noise he then quickly said in response the hard drive is supposed to make that noise. he named it the barracuda in seagates terms.