If you want to be sure that your heatsink is properly in contact with your CPU, take your computer case and place it on its side. Gravity will answer that question. If temperatures drop, the means your heatsink is not properly secured and isn't coming in full contact with the CPU.
you're making too many assumptions such as;
a) assuming he has access to gravity
on a real note, turn your pc on sideways and push down a little bit