Sorry for not getting back to you sooner and thanks for sending in a ticket to our support.
Gave you a call and left a message on your phone.
Want to learn more on what you are doing with the riser cards..
The EVGA 1300W PSU is a Continuous Power unit, it should supply you with at least 1300W 100% of the time.
I have even see some reviewers push the unit higher up to 1430W total during tests to show how much more you can get our of it.
Here is the review for reference -
http://www.techpowerup.com/reviews/EVGA/SuperNOVA_G2_1300/5.html "EVGA managed to deliver a very strong PSU of excellent quality at a bargain price. Both the G2-1300 and G2-1000 cost the same at the time this review was written, rendering the purchase of the G2-1300 a no-brainer. The latter managed to deliver 1.43 kW of power effortlessly at even over 45°C ambient by keeping all of its rails very close to the nominal voltages and registering ultra-low ripple. This is definitely the ideal unit for a high-end system equipped with three or even four high-end VGAs and an ultra-fast processor. The cherry on top is EVGA's support and the whopping ten year warranty they provide. They are the first to provide a PSU with such a long warranty period, and I think they have set the bar very high—very few companies will have the guts to follow. But competition is never a bad thing. Remember, having one or two companies dominate the field is bad since it kills motives to lower prices or produce better products." There could be something wrong with the unit you have and we can always replace it for you to see if that resolves the issue.
Happy to take your call and chat further on this to make sure a RMA is indeed what we need to do next.
Thanks,
Mike