|When you have no video, usually there's nothing actually wrong with the video adapter - usually it's merely a symptom and something else is wrong. |
Unplug the case/power supply.
Power off your monitor.
Open up the case by removing the left panel as seen when you're looking at the front of the case.
If you have a video card (in a slot - onboard video - video built into the mboard - IS NOT A CARD !), make sure its all the way down in it's slot.
A common thing that can happen with ram, even ram that worked fine previously, is the ram has, or has developed, a poor connection in it's slot(s).
This usually happens a long time after the ram was installed, but it can happen with new ram, or after moving the computer case from one place to another, and I've had even new modules that needed to have their contacts cleaned.
See response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:
Plug in the computer. Try booting.
If that doesn't help...
Failing power supplies are common and can cause your symptoms.
They often work intermiitantly before getting worse.
Check your PS.
They often partially work, fans and hard drives may spin, leds may come on, yet you may get no video and the mboard will not boot all the way.
See response 4 in this:
NOTE: some cheaper Compaq / HP models have a BESTEC brand power supply - they are a lot more likely to fail than most other brands. Open up the case and find the brand on the power supply label, or find the Compaq or HP part number label on the PS and tell us the part number so we can possibly look up who made it. If it's a BESTEC, I recommend you DO NOT continue to boot the computer until nothing at all happens, because that brand is more likely to fry something else when it has failed completely, often the mboard.
If it is failing, you can usually replace it with any decent standard sized standard ATX PS with the same capacity or greater.
Standard (PS/2) power supply size - 86mm high, 150mm wide, 140mm deep, or 3 3/8" h x 5 7/8" w x 5 1/2" d , or very close to that, though the depth can be more or less for some PSs.
Don't buy an el-cheapo PS.
See response 3 in this:
Your power supply must have at least the minumum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD!)
You can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements. Some power supplies have two or more +12v ratings - in that case, add those ratings to determine the total +12v current capacity.