Pump/s usually generate a small amount of heat so by going (Pump>Rad) it should have cooled the small amount of heat before hiting the (Cpu>Gpu>NB>etc>etc>Res)

I admit that is not always the case but it seems to be the best way & it makes sence to try and get the coolest water to the cpu first To be honest people can and do try all sorts of different orders but this way (Pump>Rad>Cpu>Gpu>NB>etc>etc>Res) seems to work the best for me and many others.

Mine is currently (Pump>Rad>Cpu>NB>Res) Hope that helps