[mythtv-users] OT. Howto diagnose machine dying/crashing

[Mark]

Combined NFS server / mythfront end box. Mythbackend on another machine uses 
the NFS.

I have a 1TB software raid ( 4 x 320 IDE drives ) and a single sata drive ( 
FC5 OS is on it ).

About every week or 10 days, this box just up and dies.  No /var/log/messages 
entries ( you just see the reboot ), nothing on the screen etc...
I have a 410 watt power supply, a couple of fans, it seems cool, low load 
etc....
I am not sure what could be causing this and I am getting no info from it that 
helps me diagnose it further.  SMART tests on the disks show all OK.  It does 
seem to be load related because I have reproduced it once by transfering a 
hundred or so gigs of data into it and it died then.  
FC5, mdadm raid..
The RAID is broken into one drive per bus ( onboard primary and secondary and 
an IDE PCI card with pri and sec as well ) I use to have all 4 drives on the 
master/slave of the built in IDE ports, but broke them up into their own bus 
as I thought that might be causing this.

Any thoughts on what to try, look for, etc....?

Thanks!

Mark