I have been carrying motherboards and hard drives through my carryon for a while now.
Full 3.5" thick drives....As I got through the WTMD I just casually say, you will see hard Drives in the bag....never asked to check it.
The ONLY time I have had to take anything out other than a SSSS nonsense time, was when I carried a softside cooler full of cheese, lots of cheese, several pounds, which they allowed after a check(they did not even touch it)