yes you can push for more!!
50c temps load in what? what are you using to stress with?
here's a guide for all gigabyte z77 includes 4.5ghz/4.6ghz and 4.8ghz oc settings,just enter you own ram speed/timings/voltage or enable x.m.p
http://forums.tweaktown.com/gigabyt...-th-z77x-up5-th-overclock-settings-guide.html
stay below 1.4v full load cpu voltage and below 80c or between 80c-85c is fine
I doubt you'd hit 5ghz
I don't know that program too well,im guessing prime95 would stress it more idk
I could only hit 4.8ghz due to delidding my cpu otherwise temps would have been 100c plus
5 minutes is nothing run it for 1 hour atleast and even then that doesnt indicate stability most of us run prime for upto 8 hrs even OCERS themselfs test their pre OC'ED bundles for minium of 8 hrs