When was it built?
Which Zalman 750W psu?
What OS? Fresh install or not? If not, where did the OS come from?
Did it ever work without doing this?
- if yes, what did you do before this started?
- if no, follow the steps here:http://www.tomshardware.co.uk/forum/page-261145_13_0.html
and let us know if anything different happens at any of the steps.