xserve G4 anf hd firewire

hello,

I have a Xserve G4 with OSXserve 10.4con four internal disk mirroring 2x500 + 2x320 mirroring with a FireWire disk to 2TB (Raid iomega 5).

Now the access to the server becomes slow, and the computer (iMac) connected to it become slow, even if the files are not on the server. If I unplug the hard firevire the server becomes faster. If I connect HD firewire on imac everything is OK.

Xserve with HD iomega worked for a few years well faster.

Then Xserve has had a system crash with a white screen, I replaced the internal disks and reinstalalto everything, but it was slow.

I tried to reset PRAM, but nothing changes, and sometimes does not restart.

Do you have any advice?

thanks

Nicola