Satisfiable speed for mid-level graphic games, with less than 900 dollar budget

I do a lot of officework: typing, creating documents, and so on. So I thought ryzen 5 3600 + 16gb ram would be sufficient enough, and I also spent a considerable amount of budget to buy a good 500gb SSD, and a nice set of game keyboards & mouse. Also, I occasionally enjoy games that do not require high quality graphics (minecraft, some steam games, etc), so I chose radeon rx 570 for my video cards. I also need to run some research program like matlab, mathematica, and they run totally fine. For bad part, It would have been better if I chose smaller case. My case seems too big and heavy. The other bad part, when I turn the power on, there is a 5 second lag until motherboard starts to operate. I'm not sure about this issue, but it doesn't bug me too much because once turned on, it is fast enough.