Reconnect the thermal sensor cable to the systemboard. Here's a closer look. Place the other end of the sensor in the clip on the chassis. Route the cable in the clips of the plastic frame.
Reconnect the front fan cable to the systemboard. Lower the fan into position and rotate it toward the front to engage the two clips as shown. Carefully route the cables through the guides in the top of the front fan.
Insert the two tabs into the rear of the chassis and rotate the PCI card holder down until the two clips at the front engage.
Lower the cover into position in the guides and close the cover.