Can someone explain what does 1:1, 3:4, 4:5 means?

[Ralphy]

4:3 = DDR200
1:1 = PC2100 (DDR266)
3:4 = PC2700 (DDR333)
4:5 = PC3200 (DDR400)

Is this just so that the cpu can run at 133mhz while the memory can run at it's specified speed (asynchronus)? Someone explain what the numbers mean?

Thanks.

 

[Mingon]

It is the ratio between FSB and memory speeds i.e if you have a 1ghz athlon (200) fsb you normally run the memory at 200mhz (pc1600)as well so the ratio is 1:1 if with this same CPU you want to use your pc2100 memory you would use a ratio of (cpu)3:4(memory). If we now upgrade the cpu for a athlon xp 1800 this runs on a 266mhz bus speed, but say you have only your old 200mhz/pc1600 memory you would need the ratio to be 4:3.