Will my HDD get damaged if i keepit on w/o MB

Hello,
I recently got a high end graphics card that requires a 500W PSU. Since i already had two 250W PSU's i decided to use two PSU's.
To one i connected the DVD drive and fan
To the other i connected the motherboard and the GPU and the Hardisk.
But unfortunately it turned out even this wasnt enough so i had to connect the hardisk with the PSU containingthe DVD drive and fans.
But i have one problem since ive connected it in such a way that both PSU's dont turn on at the same time so my only option is to turn on the PSU with the hardisk first before the motherboard containing PSU.
If i keep my hardisk on for long hours without my motherboard on will my HDD get damaged?
Plz help with positive results :-)