[ALUG] Re: Asus P5W DH Deluxe mainboard and IDE interfaces

[Wayne Stallwood]

On Fri, 2007-02-16 at 18:33 +0000, Barry Samuels wrote:

> Pass! How do I tell? Why should there be 80 cables when there are only  
> 40 pins?

The 80 conductor cables have every other conductor connected to the
ground pin. so compared to a 40 pin cable they go pin1 ground pin2
ground etc. The ribs look much finer than a 40 conductor one...if the
construction of the cable itself looks the similar to what you find on a
floppy drive then you have the wrong cables.

The reason for the extra wires is to provide shielding between the data
lines...once IDE got to 33 MB/s with UDMA mode 2 they started having
real problems with reflections/crosstalk in the cable, anything beyond
that requires the extra ground wires to work properly.

This is the same reason why you can't really mess about with IDE cables
(like cutting down a master/slave cable to make a shorter single device
one) Doing things like that over 66MB/s yields very unpredictable
results, even using the connector nearest the main board and leaving the
furthest one away unconnected can cause problems with some
drives/controllers.

> What do regard as perfect? No sharp bends, no bends at all, no fraying?
> 

Well bends that were made once to neatly arrange the cable in the
machine are fine...dents and creases that have resulted from rough
handling or the machine being pulled to bits a lot are usually enough to
make me want to change it.

Unless yours look like they have been screwed up in a ball at some point
they are probably fine. 

It's just one of those things where it is cheaper for me to spend a few
quid per machine changing even slightly suspect cables than take the
risk of having to have the machine back on the bench again under post
repair warranty with some hard to trace fault.