ok simple
asus p35 chipset has the same southbridge as the x38 asus mobo and yes some users are having issue with the p5k deluxe and permium mobos and some western digital hard drives all other p35 mobos are not having the issue it is ether a bios issue that asus did my mistake or it is a mobo disign issue that they will have to replace the mobos that are bad that being said the chipsets go like this
Northbridge (ie chipset
x38 is replacing the 975x that is almost 2 yrs old
p35 is replacing the 965 which is also old now.
intel has the (southbridge) this is where you have sata and other things
the old 975 and 965 had mostly the ich7 verisons
the new p35 and x38 have the ich9 versions