1070 strix issue

[souleater780]

so i bought a gtx 1070 strix OC and was an upgrade from my gtx 970 so i clean install the drivers then i play euro truck sim 2 good fps then dips down to 30 fps stutter then goes back up and does it again after 3 mins then i changed a couple settings in control panel changed performance to prefer max then play the game again still does It lowered the settings still stuttered.Then i decided to play another game H1Z1 medium settings i was getting 40 to 30 fps like WTF!  I did not know what to do so contacted asus and there sending me a replacement gpu what you guys think what could cause it hopefully the replacment one is better at the moment i have my gtx 970 installed no problems in game bo stutter just lower fps in euro truck sim 2 thanks for reading 

 

MY SPECS 

gtx 1070 

I7700k ]

500 ssd 850 evo 

8 ram 2400 

500W be quiet 8 series 80 plus psu