2nd display/monitor not working (strange problem)

Question

hello,
I have a mac pro with this specification...
Model Name:          Mac Pro
  Model Identifier:          MacPro1,1
  Processor Name:          Dual-Core Intel Xeon
  Processor Speed:          2.66 GHz
  Number Of Processors:          2
  Total Number Of Cores:          4
  L2 Cache (per processor):          4 MB
  Memory:          2 GB
  Bus Speed:          1.33 GHz
  Boot ROM Version:          MP11.005C.B08
  SMC Version (system):          1.7f10
  Serial Number (system):          Y***Q2
  Hardware UUID:          00000000-0000-1000-8000-0017F207E704
Display monitor Specs :
  Chipset Model:          NVIDIA GeForce 7300 GT
  Type:          GPU
  Bus:          PCIe
  Slot:          Slot-1
  PCIe Lane Width:          x16
  VRAM (Total):          256 MB
  Vendor:          NVIDIA (0x10de)
  Device ID:          0x0393
  Revision ID:          0x00a1
  ROM Revision:          3008
  Displays:
Cinema:
  Resolution:          1680 x 1050
  Pixel Depth:          32-Bit Color (ARGB8888)
  Mirror:          Off
  Online:          Yes
  Rotation:          Supported
Cinema HD:
  Resolution:          1920 x 1200
  Pixel Depth:          32-Bit Color (ARGB8888)
  Main Display:          Yes
  Mirror:          Off
  Online:          Yes
  Rotation:          Supported
Problems facing....
My cinema HD is set to primary display and Cinema as 2nd display. Everything was working fine but suddenly my 2nd display stopped working. It remains black as if its in sleep mood. The small power led light on the monitor is On(not blinking). In Graphics/Displays shows both monitors are connected. I can drag any window to the 2nd display as if its working but its still black. In display preferences it shows both monitor on arrangement section. I can even change the resolution size of both monitors.
My cinema display monitor has no problem. I have checked it already. I have swapped the DVI ports at the back of my cpu but it seems only the 2nd port is giving this problem. As if no matter what my 2nd port of graphics card is on sleep mood. I have taken it to our local apple center and both ports were working fine there, the only difference is they checked it using none apple lcd monitor. But when I brought it back to office, it had the same problem again. The strange thing is....one day while I was working the 2nd display suddenly appeared but when I restarted my mac, it went back to the same problem. Till now my 2nd display not showing anymore. I have reinstalled to new OSx but the problem remains. So can anyone pls tell me how I can solve this problem.
thanks
<Edited by Host>

Answer 1

only the 2nd port is giving this problem
You have an older card, and the second port is flaky. The problem follows the port.
I am sorry to be so blunt, but the problem is YOU.
No one wants to be the one to club you on the head and point out that your card is dying, and you are going to have to get a new(er) one. There is no "quick fix" for dying Hardware, and no fix at all for you when you will not connect the dots and realize your card is on its last legs.
If running 10.6.4 or later, you can install the 5770 and it will work, but not at quite the advertised speeds if your slot will only go up to 8x.