Dell Precision 670 Hard Drive Issues

For sata devices, make sure the boot drive is connected to the first sata port on the board. For IDE make sure the jumpers are correct. For troubleshooting, I would disconnect all but the boot device and jump as single master, or cs if that fails.

Is the cd rom unit getting power (ejects)?
PSU may have faild 12v rail for the devices

That's where I am right now.  All devices disconnected except the HD.  Tried changing the jumpers on IDE HD but made no difference.  Like I say, it won't recognise any IDE devices (i.e. Floppy and CD drives).  


I can get it to boot from external CD drive with the Windows installation disk but of course it doesn't recognise any HD to install anything on to.

Just curious, what condition is the bios battery in.  Are you having to save changes on boot and those are being forgotten?

All devices have power too, all checked with eject etc.

Can you take the floppy cable out of the mobo and try again?
Failing that take the CDrom unit cable out and test.

It sounds like your mobo IDE controller has died in which case you need to get another motherboard.
Check your IDE components by putting them in another computer if you can - just to confirm that they haven't all randomly died at the same time.
Also try changing the power supply and BIOS battery.

The disk controller chip or southbridge chip on the mobo may have died.  You may get lucky with a PCI-based disk controller board ... but at this point, I would look at replacing the motherboard.

Done that, the only device currently attached is the SCSI HD and an external USB CD drive

look at block diagram of the motherboard.  There is most likely a common chip that all of these peripherals go through.  If that chip failed then this explains everything.

One other less common thing, the NVRAM on the MOBO may be corrupted. It isn't as if it is ECC protected.  So pop the battery for 30 secs or so.  This forces a full reset of all settings.  Write down any settings you need to keep before you do this, because everything will revert to factory.

Tried that too.  Still nothing.  I suspect it is a fault with the MoBo.  

Everything points to the MOBO.  Dell does have motherboard test utilities for most, if not all of them. Suggest you download to confirm, but it seems pretty obvious that you need a new motherboard.

try Bios defaults, or update the bios.

Sometimes re-flashing the BIOS and then setting BIOS setup back to defaults and then setting individual bios settings can restore a system that has a "corrupt"ed bios, so wouldn't hurt to try that.

Perhaps you can manually set the hard disk type instead of autodetect, but that's very old school and I wouldn't be surprised if Dell bios's only applicable choice is auto.

Overall it's quite likely power supply or mobo failure of some type, so the advice to see if there are Dell diagnostics you can run is a good one.  

Often a visual examination of the capacitors on the motherboard will show some where the scored lid of the tin can is pushing ever-so-slightly up, which indicated it's failing and can cause power irregularity to affected components (northbridge, southbridge, disk controller, video, bios, chipset, etc etc) thus resulting in misbehaviour, consistently or inconsistently, and worse potentially irreversible damage.

It's rare that an electronics guru with a soldering iron can fully rectify it, and the labour cost can far exceed the cost of a replacement mobo.  Where it gets tricky is whether you can find a motherboard that takes the same socket CPU, same socket and speed of RAM, same power connector, or else a "new" motherboard could need "new" everything else, which some shops would rather sell you.   Not altogether wrong, depending on specs and age, in a throw-away world sometimes a whole entire new and faster system can be bought cheaper.  Some take a chance finding a replacement on eBay.  Some motherboards have three year warranty, so check if it's still under warranty.

It is interesting that once you get past the boot issue it seems to run Windows ok, but that's not to say there might not be some small problems over and above an inability to auto-detect the drives, so watch out for strange behaviours.

You'll want to weigh the situation and what chances to take.
And make sure you have some good reliable backup(s) set aside.

if you want to remove capacitors, here a nice guide :  http://www.capacitorlab.com/replacing-motherboard-capacitors-howto/index.htm

some companies offer replacement at a low fee :  http://www.motherboard-repair.com/index_files/Page452.htm

more info   http://www.badcaps.net/

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