Question Underperformance in games

[OmerSheeru]

I own an rx 470, and when i play games, it just bare bones gives out 30-40fps when it should be giving 60fps...cpu is not bottlenecking...gpu usage is fine...but it just doesn't change performance even after overclocking...i know my way around a pc, but i can't seem to figure this out, temps are fine too...
ALSO...in some games, it gives out decent 60...but then suddenly in an instance it drops to 30, then the next second it jump again to 60 and it keeps doing that for the whole session...why is it doing that...
NOTE:- i like to keep vsync on every game.

CPU:- i7-2600k @ 4.6 GHz.
RAM:- 16 GB 1600MHz.
MOBO:- ASUS p8p67m pro.
GPU:- SAPPHIRE RX 470 8GB.
PSU:- High Power 550 watts 80+ bronze certified(220V).
HDD:- WD Velociraptor 80GB(OS) , SEAGATE Barracuda 1TB(Games).
CASING:- Regular open case with side panel removed.
DISPLAY:- ASUS VS229.

 

[Metal Messiah.]

Kindly provide FULL PC specs.

1. "Complete" system specs should ALWAYS be accompanied with any driver, hardware, or performance question. Do not post DXDiag reports as they contain a TON of useless information. Posting a DxDiag in place of a System Spec List tends to ward off potential members from helping you.

Please supply the following system details/information:

(Complete System Specs)
-CPU make and model# (clock speed/voltage, type of cooler, and "Core" temperature @ idle and load)
-Motherboard make & model# (include Bios version if graphics card is not recognized or you are having stability issues)
-RAM (amount, clock speed, model#/link of kit, configuration)
-Graphics card(s) make and model# (clock speed, voltage if modified, Driver version and GPU temp both @ idle and load)
-Power supply make,model#, "AND" age (note if using 110V or 220V A/C input)
-HDD/SSD configuration (ie: Raid setup/ back up/ OS drive/etc..)
-Case/Chasis make,model# (fan make, model#, and configuration if having thermal issues)
-Operating System (If using Windows note Framework and service pack version)
-Monitor make, model#, and resolution (If model# is unknown list resolution and refresh rate)

*If the unit is a "laptop" or "All-in-one" system you must note the make and model# of the unit. Be sure you are ALWAYS using the OEM/manufacturer's Driver updates for the unit.

*If "Crashing":
-Note the nature of the "crash" in detail, as there are several definitions for the word "crash".

*If "performance" related issue: -Note the "exact" point in which the performance reduction occurred (ie: After Windows update, After Bios update, After Driver update, After thermal system shutdown, After Hardware change/upgrade etc...)

*For diagnostic purposes please disable the following:
-Any/all Antivirus/ Anti-malware software
-Any/all OSD monitoring software
-ALL overclocks outside of factory spec .