When I boot up it shows my 400 DDR memory registering at 166 Mhz. How do I get my 400 DDR to its full capacity? I am using an Asus A7N8X motherboard.Thanks Dan

Go to this link. Hope it helps. http://www.asus.com/support/faq/qanda.aspx?KB_ID=82957

Server is down I couldn't find that item myself. There is alot of confusion concerning ddr memory speeds. PC3200/200Mhz ddr runs at 400Mhz (ddr means double data rate). so, your memory is running at 333 currently. How do you have 640 MB of memory? Do you have a 512 and a 128 installed in dual channel or single channel? Must be single channel as I don't think it would even run in dual channel. Most memory won't run at 200 with agressive memory timings. You need to back off on them. Your processor only runs at 266FSB, correct? Asus recommends that the memory speed be set to run the same speed as the FSB for best system performance. Also, Asus has a chart of memory modules that are compatable with that MB. If you really want to attempt running at 400, I would suggest you remove the 128 stick, back off the memory timing and try again. Are you manually setting the memory settings? If so, what you are looking for is the 200 setting, not 400.

What CPU do you have...Palomino or Tbred? Are you running your CPU at 133, 166, or 200mhz FSB? Your CPU & RAM should run at the same speed for optimal performance. If your CPU is a Tbred, it's unlocked...try running it at 8.0 x 200mhz/400DDR FSB (1600mhz) & the RAM at DDR400. Set RAM voltage to 2.7v If you have a locked Palomino, you've got problems. Either you'll have to unlock it so you can set it up as above, or you'll have to clock your DDR400 to DDR266 so that it runs "in sync" with your CPU at 133mhz/266DDR.

This might help more http://home.cfl.rr.com/bjp/ComputerMemory.htm You will note that pc3200 ddr sdram runs at 400mhz BUT your front side bus [FSB] needs to run at 200mhz not 166mhz [if your mainboard and cpu support running at 200mhz FSB speed If your cpu and mainboard only support 333mhz [166mhz fsb] this means you bought better ram then your system can use.

Wanderer is right, also if you've added RAM to a board with older RAM fitted it will only run at the speed of the slowest Chip you have installed regardless.