Effect of undervolting on amperage

Adeptus

Honorable
Dec 26, 2013
2
0
10,510
I am considering purchasing two Radeon R9 280X, however; I own an 80 plus gold 850w power supply which, according to this post, is insufficient: www.tomshardware.com/answers/id-1920553/power-280x-cards-thermaltake-smart-m850w-psu.html
Would undervolting the cards reduce the amperage to an acceptable level?
 

Adeptus

Honorable
Dec 26, 2013
2
0
10,510

I have a corsair ax850. I initially thought it to be sufficient, but according to the linked post, the lack of amperage might put thermal stress upon the power supply, which I assume may reduce its lifespan.