Asus DELUXE P4R800-V - Manual (Page 26)

2-4 Chapter 2: Hardware information
Do not overtighten the screws! Doing so may damage the
motherboard.
2.2.2 Placement direction
When installing the motherboard, make sure that you place it into the
chassis in the correct orientation. The edge with external ports goes to the
rear part of the chassis as indicated in the image below.
2.2.3 Screw holes
Place nine (9) screws into the holes indicated by circles to secure the
motherboard to the chassis.
Place this side towards
the rear of the chassis