The obvious 4GB graphics card would be a GTX 1050Ti. However, your computer only comes with a 180w power supply, and the GTX 1050ti uses around 75w.....this would be cutting it too close and I wouldn't recommend it. So either you upgrade the PSU too, or go for a lower powered card like a GT 1030 2GB....which is still not a bad card, it all depends on what you are wanting to use it for.