Thunderbolt
I have two regular iMacs... If i connect the second iMac to my main iMac with a thunderbolt cable... can I use it as a second display only?
anchor.kimberly,
I strongly recommend that you read Apple's Use your iMac as a display with Target Display Mode - Apple Support article, this will tell you exactly which iMacs are compatible with Target Display Mode which is the name for what you are attempting.