Yes you can but need something to start both PSUs at same time. Something like this: https://www.amazon.com/Vantacor-Dual-Adapter-Cable-2-way/dp/B00DL3L2J6
But..... as hard drives use much less power than rest of the system (unless you have 10+ HDDs) it seems that your PSU is seriously underpowered and may present other, more serious problems.
Yes you can but need something to start both PSUs at same time. Something like this: https://www.amazon.com/Vantacor-Dual-Adapter-Cable-2-way/dp/B00DL3L2J6
But..... as hard drives use much less power than rest of the system (unless you have 10+ HDDs) it seems that your PSU is seriously underpowered and may present other, more serious problems.