no boot

I have a comnputer here that has a problem that I think might be a BIOS issue. When trhe computer is started there is no post beeps at all. What has been tried so far …
1. Hard Drive placed in another computer, boots fine with no errors at all.
2. Graphics card changed, no different problem remains, no display at all. (no onboard video)
3. RAM (512mb DDR400) has been changed, still same problem.
4. Changed power supply, made no difference, problem remains.
5. Cleared CMOS, problem still remains.

The motherboard is a MSI K8T Neo with Dual BIOS. Any suggestions as to what might be the problem?

……

I have changed the monitor, and since there is NO DISPLAY, then I cannot enter the BIOS.