PC shuts down when playing certain games

[bloody_actor]

MY gtx 970 was okay for certain months,but recently it started by refusing to display anything when i turned on my computer,I can clearly hear everything running but it wont display,the solution to this was sometimes leaving it off for a while or plug in a hdmi and it would turn on,then it started shutting down when playing certain games,my computer just shuts down when playing certain games or doing something heavy like 3d rendering,or video editing,I bought a new case and motherboard,but the problem off shutting down keeps reoccurring,what can i do guys,please help

 

[kareem.farouk]

check your psu

 

[bloody_actor]

another thing i noticed,is when i reduce my settings to medium some games just play well and the computer doesnt shut down

 

[Rexer]

-What's your gear profile? psu, ram, who made it, etc.
-Before you replace your psu, try resetting your games or go with the default settings. Games sometimes remember a crash and program it into the game. I know it sounds weird but that's why they have the 'default' or 'reset' for game settings.
-Update your computer's drivers. Check your motherboard mfg. to see if there's been an update for the bios.
-Test your ram. With your computer and psu off, drained of power (holding the off button down for ten seconds). Remove all the ram and start it with one ram stick at a time. This will also reseat your ram, cleaning the contacts and slot off.
-Again, with your computer off and drained, disconnect and reconnect all your hardware plug-ins and connections.
-Run in safe mode, your anti-virus, anti-malware and anti-spyware programs. Run the cleanup tool in C: drive. Go to Computer> right click C: drive> find the clean up button.
-After cleaning up, run the error checker. Right click C: drive> find 'Properties'> click the 'tools' tab> run the error checker or 'scan now' (check disk) (Windows likes changing the name of this button) to fix Windows. Then when that's finished, run the defragment tool and defrag it.
-One last message. make sure you're grounded to the case when fooling with the hardware. If your computer psu has a power button, turn it off (O) and keep a hand on the case when installing and reinstalling components and wiring. Being careless, I shorted my computer once and had to buy a new one.
-Try testing your computer by removing your psu and testing it t with one from another computer. Your PSU should have at least 450 watts. 970 doesn't need that much power but it helps if you add on extra components, hardware and peripherals. Picking up a 500w + is being on the safe side. Tom's Hardware has a PSU tier list that shows the best psu to the worse psu.

http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html

Hope this helps.