tnx for the answers, i have these to breakout boards, one has sync connector(floppy), one hasnt because has auto feature:
- This Breakout Board Adapter built-in Sync ON / OFF switch:
- Retains its state - Switch the button to A, if mining rig suddenly loses power, the PSU will start automatically when power is reset.
- Sync ON / OFF - Switch the button to B, the main power supply and the secondary power supply can power ON/OFF simultaneously.

so I should put brekaout board that has sync floppy connector at main PSU and other one that has auto sync at 2nd PSU?

these are the brekaoutboards:

https://bitcoinmerch.com/products/1200w-750w-breakout-board-for-hp-psu-gpu-mining-ethereum-zec-zcash-eth-w-button

https://www.ebay.co.uk/itm/Breakout-Board-for-HP-Power-Supply-GPU-Mining-17x-6Pin-PCI-e-Slots-Set-of-2/202878049656?_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D2%26asc%3D225076%26meid%3D53618420d9924325a58f76fec7f9b2e1%26pid%3D100623%26rk%3D3%26rkt%3D6%26mehot%3Des%26sd%3D352425312134%26itm%3D202878049656%26pmt%3D1%26noa%3D1%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWeb&_trksid=p2047675.c100623.m-1