what do you mean goes to standard. Which setting you refer to the "Standard"? Do you mean the Setting under:

"Battery & Performance" > "Manage apps battery usage" > "Power Saving Modes" on or off. This one?

After 1 month and after 2 set of rn3p 2gb and 3gb...i come to conclusion... My verdict...buy this phone if the battery life is you main priority,  if you prefer brand new phone and cant live with 2nd hand phone and if you can get this Phone below rm700 brand new, more than that is just not worth it........if not i think u better off with 2nd hand flagship phone from 2013, 2014...any snapdgon 800 801 will do...

What i didnt like about the phone,  ofcuz the camera,  the  headphone audio output, the dim autobrightness,  the sluggish performance its not as smooth as snapdragon 800 phone such lgg2 opo note 3 m8 and such... But but but...i stuck with this phone because i cant live without the awesome 8 hour of sot... I charge my rn3p every 2 days sometime even 3 days... I hope xiaomi or any other brand come up with flagship performance plus monster battery like this in the future.. In my book only s7e come close to my preference but i have to spend alot more for that....until s7e come down to affordable price.. Im gonna stick with this phone for awhile...

Next im gonna test the custom roms on this phone and see if i can make the experience better..

Not sure if anyone faced this issue before,i'm on ROM MIUI 8 Global 6.8.11 Beta.
Apparently there's an issue with the AUX output,the headphones which i used to plug in,is not working. the sound instead is output through the phone's speaker.
swap another earphone,same issue.
Both the earphone is tested on another device and is working properly.
Did a quick search and found out that i'm not alone. Hope they will fix this soon.
I managed to find a workaround,i half plug the headphone jack into the port,then launch the music app,play it,then fully plug into the jack.
If i plug it in directly,the sound will come out from the speaker,the headset icon on top will disappear,sometimes after unplugging it,then icon will still be there.
Did a test on CIT,and it detects my headset as plugged it even though i removed it already.