Unfortunately, I don't have an answer, and all i can keep repeating is that there's no formula to figure out how many game clients can be run on certain hardware. Unless someone has played on very similar hardware and can give detailed feedback on how it was or is, you're on your own when it comes to "budget" systems and cutting it close to hardware requirements (I use that term loosely), since the idea behind choosing hardware for multiboxing is: the more powerful, the better.

Personally, I would not want to 10-box with 16GB of RAM and 4GB of VRAM, but someone else may say that they were able to 10-box on similar hardware by playing at the lowest resolution, using the lowest in-game settings, and capping their framerate at 30 FPS.

Does that sound playable to you? To me, it doesn't.