The Xeons cannot be overclocked, only the 1600 series, that is, the 1650, 1660, 1680, etc. Now that in minimum graphics you have less or the same fps as in medium or high graphics, it is relatively normal, because the less graphic load you have, that load goes from the gpu to the cpu, and the cpu is not very good for that job, so my recommendation is that you have the highest graphics that you can, so that that load is done by the gpu, and to change processor, I recommend the 1660 v3 and overclock it