Asus gtx560 power on but no video?

recently brought the ASUS GTX560 DirectCU graphics card and have installed it on my mother board, connected the power cable and plugged in my monitor. but when i power on my pc i get no video feed even though the graphics card is powered on, have tryed it with 2 different screens and a few different cables, also tryed using my old graphics card and that works fine. Does anybody have a solution to this. Mother board is a asus P5G41T-M LX3-GB running with a duel core 3Ghz and 4gb of ram|||What size is your PSU? Whats the wattage? My guess is you havent got enough power.. the psu requires a minimum recommended 500w power supply



if you have have you connected all the cables as that will requires an extra 6 pin adapter|||3 questions

- what's your operating system, 32bit or 64bit?

- how much video memory has the old graphics card?

- how much video memory has the GTX560?



my guess is that the new graphics card causes a memory overlapping



added

did you completely remove the driver of the old graphics card?

additionally you can try this: remove one of the memory sticks and try again running the PC with only 2GB ram.



@the idiot who gave the thumbs down

inserting a new graphics card doesn't change the Hardware Abstraction Layer (HAL) information stored in the registry created during the installation of the OS. if the video ram will be increased by 512MB (e.g. from 512MB to 1GB) the result is an overlap of video ram with system ram that the operating system can't detect. increasing the video ram can lead to a BSoD or an unpredicted behaviour.