Three different motherboards. At least one ought to be like yours, right? How to connect the power button, the reset button, the busy hard drive LED and in this case even the speaker to the mainboard.
Doing this without taking out the motherboard so you see that it's doable in suboptimal situations.
Speaker special:    • How to Connect a PC Speaker to Your M...  
GPU installation:    • How to Install a GPU (Put in Graphics...