New
#11
14 passes on memtest86+ means your memory and CPU are likely pristine.
Your issue sounds like corrupted video memory. You can test it for free using passmark bit trial. Just uncheck all the other tests or it will be loud, slow and annoying. It has a CPU test as well if you're in to that sort of thing. If you have a dedicated gaming card the CPU is hardly used for most real 3D games like you're playing.
How old is this unit?
What graphics card do you have?
I'd also look inside the system for bad caps if it's easily accessible. Strange voltages being sent can also cause these issues which is what bad caps will do. Just look on your motherboard, the video card and shine through the fan hole of your power supply. If you see any swelling then you need to either replace the caps or the unit that they've gone bad in.
I have had IRQL_NOT_LESS_THAN error with a bad core 2 quad ex ONCE. It had a single bad core. The other times it has been a bad add in graphics card or bad shared video memory. This does not mean it IS one of these two issues. Those are just my experiences.