yes, In ASUS A8N SLI, I try 4 pieces of 256x4 = 1GB. Using the same brand & spec for each channel.
ie. Same pair for Blue RAM Slot, and the other pair for Black RAM Slot
The drawback for 4 pieces: it can't go higher FSB for O/C. When I use 4 pieces of A-DATA DDR600, it only reach 250 FSB...