EVGA doesn't sell any 600w units that are decent really, not for this kind of system. ALL of their 600w units are pretty much garbage or at the very low end of mediocre. The B1, N1, W1, BA, BR and BQ units are all pretty crappy. They have some good units still, a few, but none of them are 600w. They are all 550w, 650w, 750w, etc.
What is the actual MODEL of your unit, or the series, because that is what will tell the tale. It will almost certainly be from one of the series I listed above. Being "600w" or being "EVGA" by themselves, doesn't mean squat. Literally. Half the "600w" power supplies out there are lucky, extremely lucky, if they could sustain anything above 500w for longer than ten minutes, or at all in some cases. EVGA's budget units, like basically all of their 600w models, aren't nearly THAT bad, but they are definitely not anything that I'd call "good" either, not by any stretch of the imagination.
In fact, not long ago, their ENTIRE B3 series failed their testing by Aris Mpitziopoulos, who is pretty much the cream of the crop when it comes to PSU testing for all intents and purposes, because they all blew up well below their rated specifications. So, while I absolutely know that some of their power supplies, like the GQ, G2, G3, P2 and T2 units, which were ALL made by Super Flower, were very good, they have equally "very bad" models as well. I'm a big fan of EVGA when it comes to graphics cards, and if you want an Nvidia based gaming card it's almost impossible to do better than one of theirs, plus their customer service is top notch in an industry where not everybody's IS, but when it comes to power supplies, especially in the recent past and present, it's a different story.