|This is your mboard:|
emachines desktop computers usually have BESTEC power supplies.
emachines computers are well known to have el-cheapo power supplies that tend to fail more often than average, and when the power supply fails completely, they are a lot more likely than average to damage something else, often the mboard.
Unplug the cord to the computer, or otherwise switch off the AC power to it, open up the computer case, and find the label on the power supply - if the brand is BESTEC, I advise you, if you find ANY indication the power supply might be in the process of failing, DO NOT trying booting the computer anymore - if the PS fails completely there is a strong likelyhood it will trash your mboard!!!!
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.
If you're a gamer...
In most if not all cases, the max capacity rating of the PS is an intermittent rating. It's recommended that you do not load your PS to any more that 80% of that rating if you are going to be using something that puts a constant load on it, such as playing a recent game for hours on end. In that case, you multiply the min capacity stated for the system with the particular video chipset on the card by 1.25 to find the min. capacity of the PS you should get.
If you need to get a PS with more capacity, you can usually replace it with any decent standard sized standard ATX PS.
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. Don't buy a BESTEC PS !
See response 3 in this:
If you want to play recent or fairly recent games, you need a PCI video card with video chipset that can support being used with those games.
I bought a PCI PowerColor Radeon HD2400 card - it could support most recent games fine, according to user reviews on the newegg web site in the ad for it.
However it has a large (max thickness) heat sink, and that can get very close to cards in other PCI slots, if you have any.