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Almost all "name brand" computers come with motherboards that are less than desirable when it comes to doing upgrades. The same can be true of other components such a power supplies, video cards, etc.
The best bet is to have a computer custom made if you plan on doing upgrades at a later date. You should always do research on the parts you want in a new computer. There several places that make custom made computers at a reasonable price ... many times at a better price than a comparable computer by a "name brand" manufacturer.
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