The most difficult part. It is hard to get it out and put it back. It seems there are a lot of suggests how to do it easier. I spent on this about a half an hour :( Pitty that I didn't see that suggestions before.
After I have changed the thermal paste now it is possible to see 100% process utilisation and stable 3.4 GHz usage (Macbook Pro 2012 Mid i7). I’m still getting 100 degrees but seems it is ok now. To see the difference I suggest to check “Intel Power Gadget” application charts before and after thermal paste change. I did not run any special benchmarks just run some heavy task which utilise all cores (e.g. IDE code indexing)
Seems I’m facing with same issue. I’m testing temperature with “Intel Power Gadget“ application. Idle temperature is about 65-70 degree and during high load is about 100. Hope changing old thermal past will help me.