The desktops you linked to are business type computers, not made for gaming. They may have the processor speed, but like Jpkarlsen mentioned do not have a dedicated video card. They most likely aren't able to take one unless it's a specialized video card and can only take specialized types of power supplies due to how small the case is.
Yes, you will run into crashing, lag and just over all a poor gaming experience due to the computer not having the recommended specs.
You may want to save up some more money. I'd suggest $600 - $1000. This way you can afford something that will meet or exceed recommended specs of the game.
When using integrated graphics, it uses the same computer memory as Windows, Origin, the game and other programs you have on your computer.
It may work great one day and not work the next. This happens a lot with lower end computers. Issues can happen after game patches and Origin updates. The more updates and patches they put out, the more strain it is on the computer. Making it harder for lower end systems to play the game.
It is advised to survive all the game add ons, that you own a computer that meets recommended requirements, as the game is not finished and will have many more packs added to it, requiring a better computer.
