after 2.9 years half of them will have died.
i have two colo'd servers, each with two disks, hosted in a well cooled and ventilated datacenter, all four disks have had less than 75 load cycles, have never been hotter than 29 degrees celsius - but regardless of that nice environment, the barracudas suck.
the second out of my four Seagate Barracuda 7200.14 is dying, after a measly 2.9 years of constant operation. the first of the bloody things died precisely at the 2 year mark.