X38 vs P35

[veg1992]

Some X48s support DDR2. Such as the Gigabyte X48-DQ6 and ASUS Rampage Formula.

and plus they aren't worth it, since most x38 boards can be flashed to act like x48 boards i.e. Asus Maximus Formula -> Asus Rampage Formula

P35- some are Crossfire supportable, some are not (16x, 4x)
X38- Crossfire compatible (kind of pricey, usually $200+, full 16x Bandwidth)