i have a gtx 750 ti oc graphics card that requires a minimum of 400w psu and 21amps on the 12v and a 6 pin connector and have about 80w power consumption ,but my psu is 450w and have 15amps on the 12v rail and doesn't have a 6 pin connector,can i run this graphics card on 18 amps and by the pcie lane and without the 6 pin connector?