DDR ram speed issues and questions. Please help

[modem2]

Hello.

Ok here is my issue.
Firstly I have an Athlon XP 2200+ with an Asus A7n8x Motherboard.

Pretty often, it boot's normally, no errors and displays the regular information at Post it shows the amount of ram (512mb) and the processor speed (Athlon 2200+)

The motherboard speaks (on errors), so Occasionally when it boots up it says "Memory Test failed", though when that happen's it still boots and still registers 512mb of ram.

Finally, the biggest question I have is.....
50% of the time, when I turn it on and it boots, it says "Memory Frequency is 200 Mhz"

Now my question is this. What is the memory frequency supposed to run at? I know the bus speed should be 266, but what speed is the memory supposed to run at.
I believe the memory is rated at 2700 (it is ddr ram)

Now I am not totally sure how DDR ram works, does it run at half the bus speed? As in, for 266 bus does that mean it should run at 133 mhz?
When it reports 200mhz is this actaully meaning the ram itself is running at 100 mhz therefore making 200 mhz?

Or does it mean its running at 200 and actually 400?

 

[modem2]

anybody? Please?

 

[Links4me]

i don't have that mobo, but it probably means it is running at 200mhz which is actually 400mhz or pc3200......DDR
Double Data Rate transfers allows for data to be fetched on both the rising and falling edges of the clock thus doubling the effective transfer rate of the clock. For example a 100MHz DDR clock would achieve a peak transfer rate equal to that of a 200MHz clock. The effective transfer rate is equal to the clock frequency multiplied by the bus width, doubled.
so.... pc2100 = 266mhz (133mhz x 2), pc2700 = 333mhz (166mhz x 2), pc3200 = 400mhz (200mhz x 2). If it is in fact running at 200mhz (actually 400mhz or pc3200)...that is probably to fast for the memory....but if it is running at 100mhz (actually 200mhz or pc1600) then you may have a problem with your memory or even the slot on the motherboard that it is in. Did you change any settings in the bios?