Dell™ OptiPlex™ GX110
Service manual, User's guide.
View or Download the User's Guide
Messages and Codes
System Beep Codes if that applies
The most likely cause of your problem going by what info you have supplied so far, if you haven't been fiddling with wiring or anything else inside the computer case, is your power supply is probably failing.
According to the Service manual for this series your computer can be in any of three different types of computer cases. Two of them likely have an oddball smaller than standard sized power supply that costs you more to replace than a standard sized one.
If it does have an oddball smaller sized PS, depending on whether the main 20 or 24 "pin" connector from the power supply is standard sized or mini sized, you may be able to connect a regular sized power supply (it has the standard sized main connector) to the mboard for testing purposes, although it will not fit inside the computer case.
If you need more specific help, you need to supply the specific Service tag "number" on your case and tell us what it is.
Go here for how to find the Service tag "number":
Have you installed a graphics card in a mboard slot that not come with the computer, or do you want the option of being able to do that ?
Your power supply must have at least the minimum 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 ! )
If that info is not in the ad for the video 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.
The wattage capacity of the power supply in a brand name system is often inadequate regarding supporting installing any card except one with an older minimal video chipset, and that's more likely if it's a physically smaller than the standard size.
If you have already installed a video card with a fairly recent video chipset, or if you want to be able to install such a video card in the future, it's likely that you need a power supply that has more wattage capacity .