Slow startup after removing original HDD

A year ago I added a 256GB Crucial SSD to the inner Superdrive bay of my 27" Late 2009 Core 2 Duo iMac, cloned the original HDD and set it up as startup disk. Gave my iMac a whole new life.

The other day it started having a very low pitch humming noise when switched on which would disappear when lifted off the desk, so searching for the problem I opened the iMac up again and disconnected the power and data cables to the original HDD. This solved the problem.

Now I have the feeling that the it takes longer to startup and close down. Could OS X be searching for the 'missing' disk?

Thanks