I upgraded my MacBook Pro early 2011 this weekend with a Samsung 850 Pro 512GB. I followed one of the many online guides that talk about Carboncopy to copy your configuration on your HHD to your new drive and then you just have to swap them. After I did this, I noticed that the fan started to blow for anything that I started. Just opening a webpage was enough. I cleaned the fan and indeed found a bunch of dust collected behind the exhaust of the fan. That must be it, I thought. But after starting my computer, it started the fan again quite soon. Then I restarted my macbook via the old HDD on usb. Silence as I was used to before.. no fan going nuts on anything I started. So I created a bootable USB stick for a clean install. I have not heard the fan ever since. Only in cases that are normal because it requests more of my MacBook.