Yesterday, the monitor cable connected to the back of my computer got a bump, and I think something on the motherboard might have gotten hit. I say this because the monitor now reports that there is “No Signal,” and it’s still plugged into the back of the computer. I don’t have a seperate video card, and so I’m assuming the one on the motherboard is now shot. My question is, if I get a separate video card, will I have to replace the motherboard?
No. Go in to the BIOS and disable the onboard video. Install the new card and boot up.
Once it boots and you install the new drivers, go to Device Manager and remove the old video adapter.
I take it you’ve tried wiggling the connector?
What Oat said, but also make you you know if you have an AGP slot available for a video card. If not, you have two choices, either get a PCI video card (which won’t perform at the same speed as an AGP card) or get a new motherboard.
-lv
When you turn the computer on, can you hear the hard drive going through the boot process? Any startup sounds or other indications that the computer is still working?
If your video is onboard and you hit that plug hard enough to break a contact somewhere, I’d say the odds of your motherboard working at all are pretty slim. 
Lordvor, I’ve tried wiggling the connector, yes.
Meka Leka Hi Meka Hiney Ho, I can hear everything working, the fan, the hard drive, even boot up sounds. The only thing that isn’t working is the video.
I will also say that there is an off chance that a friend with a knack for such things could possibly take a soldering iron to it if the problem is simpley a loose pin on the connector. Chances of that being the case go down if you can’t get a signal via wiggling.
-lv
Have you pulled the connector and checked for bent pins?
Yes, I have, Myglaren.
Sometimes you can’t put in a new card & sometimes you can, depends on the computer & the instruction manaul. Some Dells are tricky to do.
Checked the end that goes into the monitor? Tried a different monitor? The same monitor on another computer? (Provided this is feasable, of course…) Adding a video card is gonna work find, but… Oat1957 and others seem to forget that it’s tricky to change BIOS options w/o being able to see anything. :-/
Some boards automatically use add-on video if it’s there. I don’t know what you’d do if it doesn’t.
Now it’s gotten a bit trickier. I tried a different monitor, and it worked. I’d use that monitor, except it’s an original color PS/2 monitor. However, I tried connecting the problem monitor to a different computer, and it accepts it just fine. Now I’m truly stumped.