Is there a difference between PC133 & PC2100?

[Fuzzmuncher]

Is there a noticeable performance difference?

 

[pspada]

A vast difference in terms of performance. I assume you are looking at an ECS K7S5A Pro board (or similar) that has both PC-133 and DDR sockets. Basically, PC2100 also runs at the speed of the PC-133, which is why you have both types of sockets on the board. However, the PC2100 is able to access the ram on both the rising and falling sides of the clockcycle (DDR = Double Data Rate) - which in english means it can do 2 operations whereas the PC-133 can only perform one in the same clockcycle. As a consequence, there is a considerable performance boost when using the DDR memory instead of the older style PC-133

 

[irabufan]

first, very very few motherboards supporting the most current cpus also support pc133 sd-ram
but if you compare, let's say, the difference between pc133 and pc2100 in an old athlon cpu (ie. athlon 1.33) with one using pc133 and the other one using pc2100, the real-world difference is about 15-20% as i recall
and considering the improvement of ddr chipsets over the past 2 years, i'd yes the real-world difference is significant, or at least very noticeable