Is it Safe to Run Multiple HDDs on a Seperate PSU?

I recently started using a second PSU to run my HDDs because my bottom HAF Stacker 935's PSU can't reach the top 915R. Is it safe to shut off my PC before or after my PC shuts off? Keep in mind that my OS is on an SSD behind the mobo tray on the main bottom PSU.

it's fine to shut down your drives after you shut down your pc but not before. that said I'd recommend getting a small ups and connecting your ssd to your 2nd psu'. power loss for an ssd means death.

Yeah, I may need to invest in UPS soon I'm pulling like 1500 watts from the wall, I have lots of storage devices, and I have more than one PSU. Thanks for the advice.

While we're on the subject, can anyone recommend a good UPS for a 600W PSU?

this should power your sytem for 10 minutes. you'll need to make a diy UPS if you want longer run times at a reasonable price.

but you since you have a lot of drives a raid controller with a battery might be a better solution now that I think about it.