Memory upgrade for 27" iMac, mid 2011 I recently upgraded the memory in my 27" iMac, mid 2011.  took out the two, 2 gig in the top slots &amp; put in two 8 gig units.  For some reason I wasn't thinking about putting the 2 gig units in the bottom slots.  Is this ok? Will it help any?

Thanks
It will likely work, however many people will advice you to only use matching sticks of RAM.  In other words, if you're going to use 4 sticks, ensure they are all of the speed, capacity, brand, etc.

You wouldn't build a RAID array with mismatched drive manufacturers, speeds, and capacities, why do it with your RAM?