Cause of MBP heat stroke?

[Buzz]

C2D MBP w/ SSD in main drive bay, and 750GB pull from newer MBP in optical bay w/ data doubler. Mavs on SSD main drive, w/ El Cap on large partition of optical bay HDD, and SL on smaller partition. When using El Cap or SL, the MBP can get pretty toasty, but when using the SSD, and presumably the optical bay drive is sleeping, the MBP usually runs very cool. The last few days have been hotter than words alone can describe, and even when only using the SSD, the MBP is getting hellaciously hot, w/ the optical bay area heating up almost as hot as when El Crap or SL is in use.

Any ideas on why the whole MBP is getting so much hotter when the optical bay partitions are not being accessed? And any ideas on how to help the MBP regain its cool?
Thanks.
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