[opel70]

Hello,


This weekend I was getting my HTPC ready to show a DVD for the first time after rebuilding it with pretty much all new components. Whenever I turned on DMA on the DVD-ROM and tried playing, the drive would just freeze. I spent a good 2 hours changing settings in Windows and BIOS with no change in the behaviour. I wound up having to bring the DVD player down from the bedroom and hook it up to the projector.


After all of that I did some more searching on MSI's site (motherboard manufacturer) and found one post regarding a problem with round IDE cables and a CD burner. I figured it was worth a shot so I switched the DVD drive off of the round cables and replaced it with a standard ribbon cable. Everything works perfectly now.


Is this a common problem with round cables? This was my first foray into using round cables so I have no other experience than this bad one. Was this just one bad set?


Thanks for any insight you can give about this.

 

[vmark]

I'm by no means an expert, but a little research turned up a possible problem. It seems in the 80-conductor cable of ATA66 and higher standards, every other cable is a ground cable. This was done to allow the higher speeds.


By splitting up the cables and rounding them together, you eliminate this separation and the chance of crosstalk between wires increases. My findings didn't indicate that it could cause a drive to freeze up, but it could require the drive to resend data and slow down performance. Perhaps this particular DVD-ROM drive has a problem with frequent resend requests?


At any rate, it seems there is a problem inherent in rounded IDE cables. They don't increase air flow over well positioned flat cables anyway.

 

[Bruce Lowekamp]

You probably just have a bad cable. Round cables twist each signal cable together with a ground. That eliminates the crosstalk. But if someone tries to save a few bucks and doesn't use the right quality wire, with the right twists, it doesn't work right. Or maybe a connection was missed on that one. A good quality round or flat cable should work. A poor quality round or flat may not.


Bruce

 

[Sherbona]

I've had problems in several machines that after much effort and troubleshooting, were resolved by replacing rounded cables with standard ones. Since these machines had been working when I first put them together, my guess is that the rounded cables are less 'robust' and more prone to internal breakage.

 

[tvtech1]

Quote:

Round cables twist each signal cable together with a ground.

Most don't and shouldn't, as that would mess up the characteristic impedance.

Quote:

That eliminates the crosstalk.

No it doesn't, it messes with the spec. resulting in unreliable interconnects.

The specificaton calles for a ribbon cable, not a ribbon cable that's been sliced up and 'mashed' together.

 

[opel70]

Thanks for the info. This was just a round cable that came with the motherboard. To get things working I just replaced it with my original flat cable. Since it is working I think I will leave well enough alone. Also, I do make care when routing my cable to keep them out of the way, so the round cable probably won't "help" that much anyway.


I guess I was expecting to have heard of more of these types of problems since the round cable are becoming more common. Oh well.


Thanks again for the corroboration,

 

[TheHammer]

SATA!


With that said ...I have building PC's for many years now and my conclusion has always been STAY AWAY from round ATA cables!

 

[ChrisW6ATV]

Thank you all for these comments. A couple of months ago, I bought a set of round floppy and IDE cables to 'just try something new'. I couldn't make the DVD drive work either, so I assumed it was just a bad cable. As I installed the cables, I also figured out that they are not easier to work with than ribbons, nor did they appear to improve air flow in the positions I was able to use. I returned them...and, now I will not try any round cables again either.