Bus speed

[sweetpain]

Hello,

Question.....I have a motherboard that the controler has a bus speed of 133. I have 2 drives, one runs at 133, the other runs at 66. If I put my 133 as master and 66 as slave what will the outcome be? Will everything default down to 66? Or will in alternate depending on the drive used at the given time?

Thanks

 

[HammerBot]

Older controllers would limit the speed to the slowest drive. However, I believe that most (all?) modern controllers allow the drives to run at different speed.
But the ATA66 drive will 'waste' more bandwidth since it is not using the bus very efficiently.

E.g. suppose your ATA66 drives is tranferring at 44 MB/s. That would use 44/66 = 66% of the available bandwidth. This leaves 33% or 0.33*133=43.9 MB/s for the ATA133 drive. Since the ATA133 may be able to transfer faster than this, it will be limited in speed.
However, it is not very likely that the ATA66 drive is that fast (considering it only uses ATA66 and not ATA100) and hence you may not notice any performance degradation. Also note that if one drive is idle there is nothing to limit the speed of the other drive.

<i><b>Engineering is the fine art of making what you want from things you can get</b></i>

 

[sjonnie]

Errr. If they are set to master and slave they can't transfer at the same time. But no, it won't reduce the performance of the ATA133 drive.

<A HREF="http://www.anandtech.com/myanandtech.html?member=114979" target="_new">My PCs</A>

 

[HammerBot]

No ofcourse not. They won't transfer bits at the exact same time. What I meant was if both drives were accessed simultaneously (i.e. copying from one drive to the other). In that case you will have alternating accesses to/from the two drives.

<i><b>Engineering is the fine art of making what you want from things you can get</b></i>