I have an Asus A7N8X motherboard, a XP2400+ (FSB 2666MHz) and 2 X 256Mb TwinMOS Original DDR PC3200 (400MHz) I haven’t over cloaked anything.
When I start my computer it says that "memory frequency is at 200MHz, single channel mode"
I guess the frequency is right since it is DDR memory, but should it not be dual channel mode or something?
Are my DDR-ram memories really working 100%?

Your right, if it says 200mhz it should be running at 400mhz cause it's double data rate..200mhz x 2= 400mhz. but i don't know if it would say that in the bootup screen, don't know much about your board though. usally on mine it says 400mhz if it's at 400, but in the bios it will say 200mhz. it should also say dual channel mode, try checking in the bios to see if there's an option to turn on dual channel mode. also i don't know if you made a mistake but your fdb is not at 2666mhz that the L2 cache speed or the cpu speed.

make sure you read the manual from front to back, that way you'll be a lot less likely to have to ask us for answers since most of them are answered in the manual. that goes for everyone that's new to ocing and building pc's. if you didn't read the manual READ IT NOW, it's important!!

I have solved one problem, the memories are now running dual channel mode, but I still don’t know if the frequency is 200MHz or 2x200MHz, the frequency are suppose to be 400MHz, but I don’t know if that is the current frequency. In I can’t choose a higher speed than 200MHz in the BIOS program.
There is a line in the menu “Advanced Chipset Features” named Memory Frequency, there I can choose between “Auto” or “By SPD”, if I choose Auto the line under that is named “Resulting Frequency” shows 133MHz, and if I choose By SPD the Resulting Frequency is 200MHz, the same numbers that are shown in the boot up screen.
The frequency is shown in the boot up screen. First the memory is counted and then it says “Memory frequency is at 200MHz, Dual Channel Mode”.
The only comment about this in the manual is: “Make sure the memory frequency and bus frequency setting in the BIOS are the same of set to [Auto] ensure system stability.”
The bus frequency in the BIOS are half the FSB(266MHz), which is 133MHz, but why buy 400MHz memories if I’m suppose to set the frequency to 133MHz (possibly 2x133MHz)?

I made a mistake in my original message. I was supposed to write that my FSB are 266MHz. Quite different…

Here download this and if it says 200mhz next to freqency on the memory page, your ram is running at 400mhz. if not it's running at double whatever frequency it says.

http://www.cpuid.com/download/cpu-z-118.zip