Nvidia 9800 gt (512 mb) and biostar P4M900-M4

yes, it will work with a PCIe1 board (I ran a 9800GT on a PCIe1 board for years with no problems). be sure you have enough power from your power supply for the GPU. There is also the possibility that the PCIe is disabled, or nor functioning correctly.

There will be an option in the BIOS that you can set where it looks for video first, onboard, or PCI slot, that you likely need to change the order of.

Thank u for your suggestions guys, but i have tried another power supply (more powerful than the existing one that i have) and still it doesn't work. I don't know much about BIOS, i wanted to upgrade it but i'm afraid that its causes damage to my mainboard. The video card works on other mainboard but why not mine? i have gone to see a technician to solve the problem, he says that my PCI-E slot isn't recognizing my card. I have even contacted Biostar, it says that 'P4M900-M4 motherboard supports PCI-express 16x 1.0 video cards only (first generation). PCI-express 2.0 video card is not compatible.' How can i know if my PCI-E x16 is disabled or enabled? What should i do?

thank u for ur reply. i have tried your suggestion, and the PCIx is set as for the first video for my mobo to look for. Still, the card doesn't work... i don't know what to do, plz help.