We had a DELL PowerEdge 2400 Server, shipped with two PIII 866MHz CPUs, 512M memory and two Seagate SCSI HDs. We want to build a FTP server, but SCSI HD is too expensive, so we bought two Promise Ultra100 IDE Controlers and four IBM 75G IDE HDs. Two Promise cards provide four channels, each for one IDE HD. Then I installed redhat-6.2 on it, compiled the 2.4.2 kernel with reiserfs, Software-RAID and Promise Controler support. I used raidtools-0.90 to make a Software-RAID-0 over four IDE HDs. My /etc/raidtab is: raiddev /dev/md0 raid-level 0 nr-raid-disks 2 persistent-superblock 1 chunk-size 4 device /dev/sda8 raid-disk 0 device /dev/sdb6 raid-disk 1 raiddev /dev/md1 raid-level 0 nr-raid-disks 4 persistent-superblock 1 chunk-size 4 device /dev/hde raid-disk 0 device /dev/hdg raid-disk 1 device /dev/hdi raid-disk 2 device /dev/hdk raid-disk 3 # mkraid /dev/md0 # mkreiserfs /dev/md0 # mount -t reiserfs /dev/md0 /mnt/scsi # mkraid /dev/md1 # mkreiserfs /dev/md1 # mount -t reiserfs /dev/md1 /mnt/ide I copied two ISO image files to /mnt/ide, then # cd /mnt/ide; md5sum *.iso > md5sum Uhhuh. NMI received. Dazed and confused, but trying to continue Uhhuh. NMI received. Dazed and confused, but trying to continue You probably have a hardware problem with your RAM chips You probably have a hardware problem with your RAM chips ... but if I # cd /mnt/scsi; md5sum *.iso > md5sum no NMI occured. To found what's wrong, I destroyed the IDE RAID-0 /dev/md1, built filesytems on each IDE HD, copied ISOs to each one and did the md5sum command, but no NMI occured. So I doubt the problem is in Software-RAID but not in hardware. Please help me solve this NMI problem. Thanks in advance.