I really appreciate all replies but my main concern is the compatibility of this specific server psu (-HP 684532-B21 1500W).
Ah, I see.
That product (
Breakout Board Adapter) was compatible with your PSUs. As the seller said
Compatible with server power supply:HP DPS-1200FB, 40785-001, 438202-001, 438202-002, 437572-B21, 441830-001, 506821-001, 512327-B21, 511778-001, 684529-001, 684530-201, 656364-B21,
684532-B21, 704604-001, HSTNS-PL33, HSTNS-PD11, HSTNS-PL11, HSTNS-PL18, DPS-1200QB, DPS-1400AB, DPS-1200MB, Dell PS-2751-5Q, PS-2751-LF-1F, HSTSN-PL12, PS-2112-5L, 0MYV71, 0KJYY0, 04V04J, 0783KG, Delta DPS-700LB, DPS-750RB and many more