900 GB of memory is a lot of memory on a J2900.
Provide your Operating System so one of the Intel Support Staff can help.
According to Intel® Pentium® Processor J2900 (2M Cache, up to 2.67 GHz) Product Specifications you have a low power processor that has reached "end of life".
A discrete graphics card should improve performance, but pre-built OEM PCs can be picky with that.
I suggest to ask Acer support for compatible cards.