Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
I have a similar setup and have the 520HX and I use about 160W at max(I have a piece of hardware that monitors this).
I also want to stress if you are looking to buy a PSU you want to look at a few factors like the amperage on the rails more than the total watts you can obtain, especially on the 12V rail.
Another thing is name brands, you want something with more clout rather than a no name.