Once there is enough water in the system a blue LED will enable itself. As you can see in this first stage I bypassed the VGA-cooler.
Once I was 100% certain there where no leaks I opened up the valves for the VGA-block. Now I had the system running like this for roughly 15 minutes and constantly checked whether there were any leaks. There were none.
You'll notice that on the CPU block you can place (if you want to) a small fan with blue LEDs. This is for style and aesthetics. The fan does not make any noise, it just looks fun with that blue theme going on.