Gaming Instability: Help!

[CallMeMysterious]

Hello LTT Community! Today I request help from you!

I have been having numerous issues with Treyarch's Call of Dufy Black Ops 3. It also only seems to happen when I set the program's priority to anything above low. I even tried setting it's affinity to four of my six cores, to no avail. I even tried to remove my overclock, so instead of 4.0ghz or 3.8ghz, it would be running at stock speed (3.5ghz). 

So my question is: Is this a hardware problem or bad optimization? 

Without high priority, I can only run the game at 720p low-med settings while getting 60fps, but if I do High with all or 4 cores, I can do 900p (my monitor's native resolution [don't judge]) with med-high settings while getting 60fps. 

This is extremely annoying, so if anyone can help, please do.

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RIG DETAILS:

CPU: AMD FX 6300 @ 4.0 / 3.8 / 3.5 Ghz

GPU: EVGA GTX 750 Ti FTW oc'd by 100mhz

MOBO: Asus Motherboard M5A78L-M/USB3

RAM: 1x 8gb Crucial Balistix SPORT 

PSU: EVGA 600w Bronze

EXTRA: Generic DVD Drive, Generic Card Reader, Dell ST 2010 Monitor using HDMI

[LennyIsLife]

try rolling back your gpu overclock. dunno if that's the problem, but it's worth a try