Yes, and no. There is no PC2400, according to JEDEC. It's an unofficial rating used to show the ability to _overclock_ RAM to 150MHz(300 effective). Same thing as PC150. You have to overclock the FSB to do this, which means EVERY device in your system is running out of spec, including the bus carrying data to and from the hard drives. PC166 and PC2700 are the next evolution in industry standards. No current boards support them yet, the beginning of next year we'll see that start to happen. Any PC166/2700 you see now is RAM rated at above the normal spec, but also requires FSB overclocking is most cases, exclude the Epox 8K7A which supports a 1/5 and 1/6 PCI divisor.