The most common mistakes made by people when installing their system is incorrect water block orientation and incorrect flow direction. Resulting in significantly reduced performance.

Water block orientation

Most water blocks will have two fittings enabling water to flow through them. One of these will normally be in the center while the other is near the edge. What this means when installed vertically in a tower case is that one of these out lets ends up being mounted to the bottom of the case and the other to the top. It is best having the OUTLET located at the top of your case because heat rises. If this fitting is orientated to the bottom this normally results in the top section of your water block being filled with warm water because it is unable to escape easy.

Flow direction

It's important to consider which way the fluid will be flowing though your water block since incorrect connection will effect system performance greatly. In most cases you will have two fittings one that's in the center of the water block and one that's near the edge. It's important that the coolest water is pumped into the center of the water block then removed from the edge.