Yes, you can. The motherboard is equipped with a PCI-e port so you can plug in a graphics card.
Yes You can upgrade the video card
One can purchase a Dell OptiPlex Gx520 online on websites, such as Overstock, Amazon and Tiger Direct. Dell OptiPlex Gx520 comes in different configurations.
No, by default GX520 comes with a built-in device which is CD player and burner + DVD player.
Used Dell OptiPlex GX520 computers are offered for as low as 66 EUR till 99 EUR at eBay. Besides that no items have been found for example at Amazon or Best Buy.
Windows ultimate
Dell's Optiplex GX270 is capable of running many current and popular games like World of Warcraft and League of Legends. However, performance is not particularly good unless you upgrade the system's graphics card. Most default graphics cards are not impressive for gamers.
Laptop graphics cards are generally considered to be impossible to upgrade.
By upgrading the graphics card.
You can upgrade your laptops graphics. You will need to see what type of graphics cards your computer is compatible with a choose one to your liking.
Not with the video on the mother board. It requires a video upgrade, in the agp slot
Dell optiplex 755 is newer Between the gx620 & the 755 there was : the gx620 then optiplex 320 optiplex 745 optiplex 330 optiplex 360 optiplex 740 then the 755 Also, the newest optiplex is 9010
No you can't.
There are some minor differences between the OptiPlex 745 and 755 from Dell like different chipsets options and graphics cards. The 745 uses a Q965 Express chipset, while the 755 has a Q35 Express chipset. The 745 does not come equipped with a graphics card and the 755 does.