Can you use an IDE cable backwards?

mathias · Post by **mathias** » Thu Nov 25, 2004 8:54 pm

I know I'd probably be able check this myself, but I'm a little paranoid about data corruption or even drive failure, so can the IDE plug at the end closer to the middle plug be pluged into the IDE controller (MBoard), and two drives plugged into the other plugs?

tay · Post by **tay** » Thu Nov 25, 2004 10:13 pm

Yes should be fine,

P-ATA is a bus with a master and slave. So when a drive is driving the bus (by sending data) both the MB and the other drive see it. Each device (controller and drives) are driving the bus at different points so there is contention resolution in the master slave distinction. This suggests that there should be no drive or MB failure because the MB should be able to deal with both drives requesting something at once. I am not aware of IDE protocol details however :not a nerd:!

This may not WORK, but it is highly unlikely that it will cause damage to your drive or MB IMO. There is no electrical funny business that can happen this way that I am aware of.

Zyzzyx · Post by **Zyzzyx** » Fri Nov 26, 2004 12:07 am

I've run IDE cables in either configuration, no problems at all.

And actually, in my most recent build I simply removed the middle plug completely. Still no problems.

soujir0u · Post by **soujir0u** » Fri Nov 26, 2004 2:07 am

I wouldn't recommend it, I've encountered problems with some machines set up this way. I've also read that connecting the IDE cable the other way round gives slower transfer rates.

I don't have the scientific explanations or proofs for this though...

teejay · Post by **teejay** » Fri Nov 26, 2004 4:11 am

You'll be fine probably, just don't jumper your connected disks to CS (cable select) as is more or less the preferred way with ATA66 and up. Explicitly choose your master and slave disks and it should work. I'm sure I've read somewhere that this will lower performance but I can't find any info confirming that at the moment. Just try and see, use a benchmarking tool if you want to be sure.

Worst thing that can happen is that one or both disks will not be detected, corruption is impossible to achieve in this way, you'll need more drastic measures. Oh, wait, you weren't looking for an excuse to upgrade your drives... that was me

mathias · Post by **mathias** » Fri Nov 26, 2004 8:19 am

teejay wrote:Worst thing that can happen is that one or both disks will not be detected, corruption is impossible to achieve in this way, you'll need more drastic measures. Oh, wait, you weren't looking for an excuse to upgrade your drives... that was me

I don't see how this could damage my whiny spinpoint, while leaving my Cuda 4 intact.

I have lot's of uses for an extra drive anyway.

After putting my main drive on foam on styrofoam, I found out the IDE cable is actually long enough normally, so instead I think I'll probably just look for an extra short IDE cable.

I've read on a Spinpoint instruction instruction page that that this is okay with regular IDE cables, but not with UDMA ones.

Jan Kivar · Post by **Jan Kivar** » Wed Dec 01, 2004 5:13 am

soujir0u wrote:I wouldn't recommend it, I've encountered problems with some machines set up this way. I've also read that connecting the IDE cable the other way round gives slower transfer rates.

Reversing a PATA cable will force the devices to use ATA33 or lower. IIRC the extra grounding wires are connected only from the motherboard's connector to the middle connector.

Also, as previously mentioned, cable select may not function properly with a reversed cable. Maybe it will work with just one device, and not with two.

Cheers,

Jan

halcyon · Post by **halcyon** » Thu Dec 02, 2004 12:28 am

Jan is correct. I definitely wouldn't recommend using the two-coloured (blue/black) UDMA66 (or later) connectors in reversed position.

The connector is only earthed at blue end which should be connected to the motherboard end (which has grounding connected).

It's not a coincidence that the connectors are coloured and all motherboards clearly state that one should plug the blue connector to the motherboard and not a device

teejay · Post by **teejay** » Thu Dec 02, 2004 3:05 am

OT, I know, but I get curious sometimes (ok, a lot): what is the point of a grounding wire if it's only connected at one side? Or am I missing something?

Tibors · Post by **Tibors** » Thu Dec 02, 2004 3:31 am

It's not a grounding wire to ground the drive. They are shielding wires. Shielding the other wires from each other. They are grounded, because otherwise they are less effective. (Don't ask me the exact science behind this.)

Box · Post by **Box** » Thu Dec 02, 2004 4:02 am

I thought it'd be better to ask the following here rather than opening a new thread, so here I go:
Would it be in any way harmful to just cut of the second device connector, in order to get an IDE cable with only one connector?
Reason I'm asking is because I intend on assembling a pc which will probably never get a second HDD, and cutting of the excess spares me the work of trying to get rid of it in a neat manner.

lm · Post by lm » Thu Dec 02, 2004 5:32 am

Box wrote: Would it be in any way harmful to just cut of the second device connector, in order to get an IDE cable with only one connector?
Reason I'm asking is because I intend on assembling a pc which will probably never get a second HDD, and cutting of the excess spares me the work of trying to get rid of it in a neat manner.

How about making that system Serial ATA?

Jan Kivar · Post by **Jan Kivar** » Thu Dec 02, 2004 6:51 am

Box wrote:I thought it'd be better to ask the following here rather than opening a new thread, so here I go:
Would it be in any way harmful to just cut of the second device connector, in order to get an IDE cable with only one connector?
Reason I'm asking is because I intend on assembling a pc which will probably never get a second HDD, and cutting of the excess spares me the work of trying to get rid of it in a neat manner.

Here's a thread where no mercy is given to PATA cables.

And here's the guide found in the thread.

Do it with your own risk though (see the discussion in the first link).

Cheers,

Jan

Box · Post by **Box** » Thu Dec 02, 2004 10:25 am

lm: S-ATA is not an option because that system I'm putting together will be made up of old parts I had lying around. The motherboard doesn't support S-ATA, and I'm not planning on buying a controller for it (if those things even exist).

Jan: thanks for the link. I think this sort of confirms what I thought and what I was hoping for: I can do just about anything with those cables as long as I put the connectors on correctly...

*edited for bad spelling*

DanceMan · Post by **DanceMan** » Thu Dec 02, 2004 3:21 pm

Tibors wrote:It's not a grounding wire to ground the drive. They are shielding wires. Shielding the other wires from each other. They are grounded, because otherwise they are less effective. (Don't ask me the exact science behind this.)

Some similar science is used in professional audio cables and devices, called balanced line. The outer braid on mic lines is used for shielding only, not for signal. I'm over-simplifying -- there are transformers involved in the gear also.