Try connecting the DVI/VGA/HDMI directly to your Motherboard and if you get signal from your motherboard power off the machine and try taking the graphics card out and then back in, may not be inserted properly.
Also I have heard of pci-e 2.0 cards that do not work on old pci-e 1.0 motherboards. The standard is backward compatible but that doesn't mean there cannot be problems.
Also I assume the CPU is single core. Perhaps Pentium 4. It is too weak for that GPU. Even Pentium D is probably too weak.