The top one looks like a War coral, (Favites) but I'm not really sure about the two in the second picture. The one in the foreground might be a Caulastrea and the one in the back could be a Favia/Favites as well.
Can you describe what it is your seeing when they die?
The first pic is my main concern, it starts to turn pale like it shows towards the bottom of pic. Then slowly just dies away leaving the skeleton.
The other two are not dying, they just do not grow and I've had them for a year.