|If you find that a known good power supply DOES make your system work fine, then in most cases, you can usually replace the original power supply with any decent quality 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 (in quality) PS.
Don't buy a BESTEC power supply !
See response 3 in this:
If you have a video card installed in a PCI X16, PCI-E X1, or a PCI slot, you MAY need to get a power supply that has more capacity than the original one does.
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 find that a known good power supply does NOT make your system work fine, your USB ports etc. still do not work, then your mboard is damaged.
According to this excellent third party web site:
if your W3502 model was bought in North America, this list
states that this is your mboard - Intel® D101GGC (Grant County) Mainboard - unofficial info:
It's a genuine Intel brand mboard model, that has an emachines bios version on it.
(DO NOT use an Intel bios update for it ! )
In this case, the other components - at least the cpu, ram, drives, etc. - of your system are probably not damaged. You could test the keyboard, mouse, USB devices by connecting them to another working computer.
If you search on the web using this mboard's model and emachines, or search using any of the emachines models listed on the e4all support page for this mboard, and replacement motherboard or similar, there are often used mboards on the web available for a reasonable price that have the emachines bios version. However, make sure the ad says the mboard has been tested and it is known to work (otherwise it may have been damaged by a BESTEC power supply).
You can use any mboard that your cpu and ram is compatible with, or that the cpu is compatible with and get different ram cheaply, or use the same mboard model that has an Intel or other brand name system bios version on it, however, if you have already made a Recovery disk set for your emachines model by using a program supplied by them, or if you want to be able to use a Recovery disk set you can often buy from the emachines web site, then if this same mboard model has an emachines bios version, you will have no problem using the Recovery disks - if it doesn't have an emachines bios version, or if it's a different model, you probably will not be able to use them - they will probably refuse to install.
Check for Recovery disk availability -
Accessories - Purchase Accessories, eRecovery CDs....
If a disk or set of disks is available, it's usually MUCH cheaper to buy including shipping than buying merely the cheapest type of XP CD available - a regular official Microsoft OEM XP Home CD.