The present study numerically investigates the impact of modified butterfly inserts, where the consecutive inserts are perpendicular to each other, on the thermohydraulic performance of a square copper minichannel heat sink using deionized water cooling. ANSYS Fluent 2021 R2 is employed to scrutinize two discrete pitch lengths, 10mm (m-MCHS-BTI-10) and 5mm (m-MCHS-BTI-5), within laminar Reynolds number range 200 to 900. Results indicate friction factor enhancement ratio, which is a measure of rise in pressure drop of the enhanced configuration compared to a plain minichannel heat sink, attains value up to 4.97 and 6.89 for m-MCHS-BTI-10 and m-MCHS-BTI-5, respectively, at the highest tested Reynolds number. At a Reynolds number of 900, the Nusselt number enhancement ratios are 2.49 and 3.95, respectively, for m-MCHS-BTI-10 and m-MCHSBTI-5 cases indicating the significant improvement in heat transfer. Furthermore, using Performance Evaluation Criteria (PEC), the insert's overall performance is assessed, resulting in a range of 1.08 to 1.46 and 1.4 to 2.07 for the m-MCHS-BTI-10 and m-MCHS-BTI-5, respectively across the studied Reynolds numbers. Additionally, modified butterfly inserts in this study show PEC value improvement of 4.10% − 12.52% and 13% − 28% for pitch distances of 10mm and 5mm, respectively, compared to conventional butterfly inserts, across the studied Reynolds number range.