Windsim fans not spooling

Hi im using SIMHUB and im having problems with my DIY windsim. If ii use some cheap low power fans they spool up fine but produce very little wind. as soon as i fit more powerful fans they wont spool and just twitch, its as if they are not getting sufficient voltage to spool up?

I've checked the wiring and all is ok and if i connect direct to 12v they spin up fine.

fans are specked at 12v 0.6 amps and I'm using a 12v 80watt PSU.

Any ideas as what wrong? it defiantly seams to be not enough power to get them spinning