Idle Spin Noise on 1TB & up

[RAYTTK]

Hi I seem to Have hit a brick wall here and am in need of some suggestions, First off I have my PC in our family living room and its on 24/7 working, so I have all on water and fans on low and up until now its been near silent.
I have 2 x Intel 80 gb raid O for my C drive, I have 3 x WD 640 CavBlack sata3 drives for storage and writing to and from, Everything works great, very fast
But I have so many Projects/Files to store I'm running out of space. With the amount of DVDR's I have the option to just add another HD is out so I bought a Samsung F3 1TB, It has a really annoying spin noise all the time
I bought a Seagate Baraccuda 1.5 TB and that has 4 seconds of silence then 6 seconds of spin noise
I Know this is OCD but its really doin my head in as everytime there is silence in the room the drives noise are there. I dont mind noise when the drives are working but why is it there when they are Idle?
I have remounted the rack with new rubber pads and gromets on the drive screws but it does nothing so I sat the drives on elastic and still the noise is there.
Are all 1tb + Hds noisey ie more platters more spin noise?
does anyone have a quiet 1tb + to recommend

[Anvil]

YMMV but I've found WD Green 1.5-2.0TB and Samsung F4 2TB to be the quitest HDDs.

I guess there is some variance depending on firmware as I've got some ST LP5900 2TB that are very quiet (once they've started) and some seem to do some sort of house-keeping from time to time.