You cannot change the integrated graphics. However, since you have a desktop PC, it is very likely that there is a PCIe x16 slot. If so, then you can add a graphics card, such as one with an NVidia chipset, or one with an AMD chipset.
Check if there is an appropriate empty slot on your PC. Then, decide on the graphics card you want by looking at various cards, perhaps on a site like Desktop Graphics Cards | Video Cards - Newegg.com.
Careful - make sure, in addition to having the correct slot, that you consider the physical space, air flow, power required, and power connections. For more specific information, you may want to ask Contact Support on the gateway site.
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