# Have I bought a dud motherboard?

## Bert365

I've been happily using Gentoo for a few years, on an Athlon XP-based system.  I've just bought the overclocker's favourite Pentium D 805 and a motherboard to suit, so I'd like to recompile my whole system for my new gear, keeping the old hard disks, both of which are Seagate Barracuda SATA jobs that have never given me any bother.

So I downloaded the latest minimal install CD, with the intention of chrooting into my old filesystem, fiddling around with the various flags, reconfiguring the kernel and letting it get on with it.  But the boot process is very erratic - sometimes it doesn't find my hard drives, sometimes it does, but reports read errors and I can't mount them.  In short, I've never yet managed to get my system to a state where I can do anything apart from use what's provided on the CDs (it'll happily boot Knoppix, by the way, but the same hard disk problem occurs).  The motherboard itself also seems to occasionally fail to report that it's found the harddrives at startup.  It's all a bit strange and there's no pattern to it - sometimes it works, sometimes it doesn't.

I'd love to reproduce these errors here but unfortunately my home broadband's down at the moment and I can't get anything off the machine, so hopefully I've said enough for somebody to have a clue what's going on.

The motherboard's an Asus P5ND2-SLI Deluxe, which uses the NFORCE 4 SLI chipset.

Is it most likely that the motherboard's defective, or is there some known issue with this board/chipset, SATA drives and Linux?

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## NeddySeagoon

Bert365,

You can't chroot into your old filesystem if it was made for an athlon-xp, much of it won't run on a P4 because of a sprinkling of instructions the athlon-xp has that the P4 doesn't - you need a whole new install.

That doesn't help with your motherboard issues.

You have ruled out the install CD, Gentoo and Knopppix both do it.

Check for damaged and not properly seated cables ... look at power cables too.

It could also be a PSU issue, is the PSU a bit marginal ?

Compare the Vcore regulators on both boards. Older ones generate Vcore from the 5v supply.

Newer ones use the 12v supply and have the facility to connect an extra connector (or a 24 pin ATX power connector).

Shifting the CPU core power this way can cause 'brownouts' on a marginal +12v supply.

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## Bert365

Power supply's a possibility, I suppose, I haven't upgraded it and the new CPU, graphics card etc. draws a fair bit more juice than the old stuff.  Although I'd be surprised if it maxed it out, but it might explain why things sometimes work and sometimes don't.

Incidentally, even if the hard drives are found by the BIOS, the system still can't mount them on boot, I'm not sure if that was totally clear in my initial post.  I've certainly checked all the cables and that sort of thing - obviously it was the first thing that occurred to me.

So I'll investigate the PSU route further, but am I right in taking it from your post that there's no reason why even the most up-to-date Linux kernel would have trouble with my kit?

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## NeddySeagoon

Bert365,

Your boot troubles are nothing to do with the kernel. If your 12v supply was marginal, the drives may take too long to spin up, so the kernel times out waiting for them to become ready. Then as far as the kernel is concered, they are not there. They may also go not ready if the spin speed goes out of tolerance later.

Its not so much the absolute power rating of your PSU, its the distrubution of the available power between the various voltages.

What happens if you reduce the 12v load by disconnection all but one hard drive ?

Does the remaining drive detect reliably ?

Try all you hard drives one at a time this way.

Now try all the combinations of two, three ...   etc.

Every time you add a drive, you are adding to the +5v and +12v load.

If it works with any subset of your drives but not them all ... it points to a marginal PSU.

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