Gpu O/C

Well it's my first time o/cing a gpu so I need to ask a few questions.

1. Is MSI Afterburner just for MSI gpus? (Would use CCC but I saw that msi has the voltage adjuster that I might need.)
2. Whats the safe temp my card be around when o/c at 900+/1250+?
3. I have a 520w antec neo eco psu holding up my system. I read around and heard that you want to keep your psu load at 50% or lower, more could cause psu to fail and take out some of your computer parts. Is this true? My psu

1. Nope, you can use Afterburner on non-MSI cards. You need to have a reference XFX 5770 for voltage control, so you may or may not be able to adjust your voltage.
2. I would try to keep temps under 80C, but that's just me.
3. I don't know how good the Antec Neo Eco PSUs are, but PSUs should be able to handle 100% load at their rated specs or they're defective.