After PSU repl computer freezes after 10+ mins of gaming

[Beetoz]

I replaced my PSU recently to Antec HCG 750 GOLD .. 15 seconds into BF3 game (or 30 seconds into League of legend) , pc freezes .. black screen .. sounds is on a infinite loop of the last  0.5 second before it freeze

So I exchanged it for another Antec HCG 750 ... now it does the same thing .. but after 10 to 15 minutes of gaming ... what are the chances of 2 new defective PSU? ... i emailed Antec to see if this PSU was pre 2018 and they told me it was build late 2020

 

other than gaming .. the computer runs fine while browing or youtube and etc .. only happens during gaming

 

Mobo: Asus Z97-A
Cpu : i7 4790k stock with NH-D15s
Gpu : Asus Strix gtx 970
Ram : G.SKILL Ripjaws 2x8GB) DDR3 2133MHz (xmp)
Sound card : Creative sound blaster Z
SSD : intel 520 120GB (C) , WD Barracuda 1TB (D)
Psu: Antec HCG 750 GOLD (Seasonic X-760 gold 80 modular <--- old PSU)
Case : Lianli lancool II Perfomance
Key-Mouse : Corsair.K70 - Razer Deathadder V2
Monitor : Dell S2721DFG 2K 165HZ ips
OS : Windows 10 pro educational 64 bit