The present research article focuses on the problem of flow and thermal non-uniformity in a microchannel heat sink (MCHS). A concept of variable size approach is employed to mitigate flow and thermal non-uniformity in I-type MCHS. The heat dissipation requirement of an electronic chip of 8^th Generation Intel Core i9−8950K processor of 10 mm × 10 mm size is considered in the present study. It is observed that proposed design improves flow uniformity by 91.1% and thermal uniformity improves by 70%. It is also observed that proposed design decreases maximum temperature of chip surface about 3.93°C.