Not the fan. That would not cause a blank screen unless the card is overheating, but you stated no signal from the start. It could be a motherboard issue, but is most likely a faulty card. If it's an old Dell, I would look for a cheap replacement graphics card.
I think you are right. I should have told you I already removed the card and the PC booted up.I reconnected my screen to onboard graphics and also changed the the bios menu to use onboard but monitor shows windows booting and then suddenly shows message "vide signal out of range" or something similar.Should I try to start in safe mode to change video settings to lowest settings. I assume settings may be set to high as they were set for the 4670.Thanks