Scenario: 
OS:          System Running Suse 8.2 Linux Pro 
CPU:         AMD Athlon 2100+ 
Motherboard: Asus A7V333 Motherboard
Memory:      512 Ram
Hard Drives: 2x 60GB IBM 
Options:     Promise TX2000 Raid Controller
Options:      Raid (Mirror) of both drives

Recently a motherboard died on that system and we wanted to get away
from using AMD and switch to Intel P4. We got Intel D845GEBV2 and
Intel P4 2.5G CPU.
When we put in the hard drives and tried to boot the system was
running a kernel compiled for Athlon and it wouldnt boot. Is there any
way to work around this and recompile a kernel without having to
reinstall the OS?

Skunin,

The short answer is: boot from a live CD, mount your hard drive,
chroot into your old file system, and recompile your kernel.

The nasty part is that, so far as I know, no live CD has support for
the Promise TX2000 SATA RAID controller, so you won't be able to see
your drive or mount it.

The alternative is to download the Promise TX2000 drivers for Suse 8.2 from here:

http://www.promise.com/support/download/download2_eng.asp?productId=88&category=All&os=100

Extract this to a floppy.

NOTE: Since you have mirrored hard drives, it may be best for you to
take the second drive out of the system and put it aside as a backup
before you proceed. That way, if you make a mistake, you have a
pristine system with which to try again. You can put it back later and
rebuild the mirror. I am assuming from your question that the drives
are mirrored in a RAID Level 1 configuration, so that they have
identical content. If this is not the case, then you cannot remove one
drive.

Boot from your Suse installation CD, select "Rescue System" from the
boot menu, and issue the following command at the "Boot:" prompt:

ide0=0x1f0,0x3f6,14 ide1=0x170,0x376,15 ide2=0 ide3=0 ide4=0 ide5=0
ide6=0 ide7=0 ide8=0 ide9=0

This is a workaround for 2.4.x kernels misidentifying the Promise controller.

Once you have finished typing this, put the floppy with the Promise
drivers into the floppy drive and hit enter.

The Suse rescue system will search the floppy for the Promise driver
and load it, giving you access to your SATA drive. I have tried this
on my current system with Suse 9.0. It appears to work fine, but I do
not have a Promise TX2000 to verify that the driver actually works.
According to the boot log, the driver is loading.

Log into the Suse rescue console with the user name "root" and no password.

Check that you can see your hard drive with:

fdisk -l

Then "chroot" into your old system and compile the kernel with the
appropriate options. You may have to mount the floppy under the old
system once you are chrooted and run the install script for the
Promise drivers, something like:

mkdir /floppy
mount /dev/fd0 /floppy
cd /floppy
sh install

The Promise TX2000 has been a bit of a Linux bugbear. I built a system
with one of these in it a while ago, so I can attest to this. Here is
some information about Linux support for the TX2000 in case you have
trouble getting the driver running:

http://www.linuxquestions.org/questions/archive/8/2003/08/2/78709

The direct link to the TX2000 driver for Suse 8.2 and 9.0 is here:

http://www.promise.com/support/file/driver/4_ft2xssb2.zip

This is the one I used successfully.

Best Regards,

Alan Kali

P.S.

If you remove one drive, you may have to reconfigure the Promise BIOS
so it doesn't look for the other volume in the RAID array. If I
remember correctly, you can disable the RAID function in the BIOS, and
have the Promise controller talk to the remaining drive as a single
drive.

Alan Kali

P.P.S.

After doing the "fdisk -l" command, your old file system will not
necessarily be mounted. You may have to use the mount command, along
with the output of the fdisk command, to mount the file system.

I assume you know this and much more, since you mention recompiling
the kernel, but if you need more detail, let me know.

Alan Kali