Yup, I agree with the other poster, it's pretty close.  

I searched earlier in one of the S1 Setup forums and read EACH BLADE requires/draws ~15 amps each - so, basically ~30 amps total for each S1 under stock mode.  

Just make sure you check your PCI-E wires on BOTH ends and see if they get super hot.

EDIT: BTW, in one of Sushi's threads, it's "recommended" that you have ONE SEPARATE 12V PCI-E cable (non-splitted) to EACH S1 Blade for safety reasons.