Hard Drive high temperatures

I am installing 5 seagate enterprise 15k rpm 600GB hard drives in an Intel Chassis SC5600BRP with a 6 drive hot swap expander cage. The drives are configured as one RAID 5 array. The drives get extermely hot (up to 80 degrees centigrade, read from Intel RAID WWeb console). As a result I have had 3 hard drive failures in last 10 days. I heard from someone that having 5 drives in RAID 5 creates too much activity between the hard drives and that is why they get so hot. If any one has any comment or suggestions, I appreciate it very much

Ahmad