(redirected) Precision 690 doesn't boot up

I have 8-9 years old Precision 690 with, dual Xeon 3160, dual nVidia Quadra 4500, dual SCASI Hitachi 150GB, raided hard drives. Computer worked fine until it stopped booting up.

On start up it doesn't show Dell logo with Bios A 06, as it should.

Does this suggest that the problem is with Motherboard, boot up Hard Drive, or perhaps the Operating System?

Any suggestion will be appreciate.

With thanks.

Dragan Mikki