GELI encryption and HDD critical temperature

[s.g.]

Guys,
I notice occasional overheating of my GELI-encrypted hard drives 
followed by the reboot.
This happens when there is heavy activity on the drive - eg when trying 
to dump partitions.
There are 4 drives i have, three encrypted and fourth is plaintext.
According to smartctl -a, the temperature of the encrypted drives is 
~59C. The temperature of the unencrypted drive is, however,  ~41C, 
according to the same smartctl -a.
All the four drives in question are Seagate ST3400620AS/3.AAC, GELI 
encryption is default AES, no data authentication. This is on 
6.2-RELEASE-p8.
Am I right assuming  GELI encryption is the reason for such a "global 
warming"?
Thanks in advance,

Grigorian