945GCM478 refuses to work with ATI HD5750!?

Question

Hi everybody.
I own the MSI 945GCM478 since October 2008 and I was pleased with it, but now I'm facing a problem.
Recently I've bought a Gigabyte GV-R575D5-1GD graphic card (using ATI HD5750 chip), which does not work with MSI motherboard. The graphic card works fine on other motherboards (tested).
But with 945GCM478, I power up the system, all coolers start spinning, but after 5 second they stop, only to restart again after 1 second, and so on ...start, stop, start, stop. The graphic card does not display anything in this time. So what does a reasonable person think in this situation... the power supply isn't up to it (although I've read that this graphic card isn't very demanding)! So I get angry and buy a Nexus RX-8500 PSU which should be enough I thought. But to my stupefaction the behavior of the system was the same. I've tested other 2 PSU with the same results. On the same occasion I also tested a nVidia GeForce 9500
graphic card which worked fine. Also two months ago I tested the system with a GeForce 9800GT graphic card ... no problem.
In the mean time I've updated to v1.1 bios... so this could be a problem. I reverted to v1.0 bios and tried again... no results.
I don't know what else to try.
So I'd like to ask if anybody have experienced anything similar, or can drop some light on the issue.
Could be a bios/chipset/PCI-E problem, or my motherboard is just faulty?
Is there any solution to make the HD5750 to work with 945GCM478?
The system uses a 3GHz Pentium 4 which complies to the minimum requirements in the graphic card manual.
Thank you in advance for any suggestion. (Please excuse my English).

Answer 1

i.
The system consist of
Motherboard: MSI 945GCM478;
Processor: Intel Pentium 4 HT (Prescott,FSB800,1MB);
RAM: 1GB x 2 Kingston 800MHz (running in dual channel at 667MHz);
HDD: Western Digital 160GB SATA2, Maxtor 200GB SATA1;
OPTICAL: DVD-RW LG;
PSU: Nexus RX-8500
AC Input    115V/230V   15A/7,5A  50/60Hz
DC Output              +3.3V   +5V   +12V1+12V2+12V3+12V4   -12V   +5VSB
Max Output Current   24A   30A     20A     20A      20A   20A   0.8A   3A
Max Combined Power      170W      760W                    6W   15W
Total Power          829W
Also I would like to mention another thing, which raised my suspicion at first:
before I tested the graphic card on my home system I tested it on job system, a Lenovo using Intel 946PL/GZ chipset / Intel Pentium D 925 (LGA775) / 1GB DDR2 667. Initially this system refused to boot also with the graphic card, producing several beeps.  It did started only when I set in the the bios the active video device as Internal (not Auto or PCI-E) but the inserted graphic card didn't displayed anything, although the cooler was running.
I hope this helps.
Thank you.