Core clock will probably restart your pc if too high, or break the graphics driver.
Memory will likely crash the game.
Look out for artefacts, if they are happening you are essentially on the verge of damaging your card.
150/500 is the most I can do. Most of my gains were increasing the voltage curve, which gets the boost clock much higher, but I'm not going higher than +30% even though higher is stable.
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1080p will go higher framerates and may push your clock speeds higher, which is why there is less stability there. 4k is harder to run, but high framerates are another thing.
Try running firestrike. If that crashes then lower your memory.
Since the laptop is pretty new like 2 weeks barely, and I can alot of games at 120fps, I doubt that's it.
Anyhow I think I figured it out.
I just tried Redout's demo. Everything maxed out and 60fps. All good. Switched the fps cap to 120 and the game crashed soon on starting the race. I overclocked gpu to +150/+300 and ran. Still crashed (device removed error).
I then saw that my laptop was on ECO setting (I keep it on that normally). Changed it to it's default "Sport" and now ran the game. This mostly changes CPU performance and power draws*.
It ran perfectly on 120 fps and I completed the time trial with a Gold medal. I under clocked my GPU to -150mV and tried the game. (my default settings as I see a 4C drop with no noticeable change on performance).
Ran Crysis 3 now and getting 120 fps locked too with no crash whatsoever.
I guess its most likely CPU clock speed interfering, causing an out of sync issue or maybe power draw. Thinking of grabbing a 330W power brick.
EDIT: Fire Strike gave me no errors or artifacts (<- Thank GOD). Ran it with the Base settings except for -150mV GPU under clock. Scored 13291 which I think is inline with notebookcheck's 13974 w/o under clocking.
However I had Afterburner's FPS OSD running with the show Limit option on. And when the GPU Usage reached 98-100%, Lim: Power would show up. Could ultimately be power draw causing issues perhaps.
EDIT 2: Ghost Recon Wildlands had issues with crashing as well. Chainging laptop to Turbo setting though (4.0 GHz default) solved all issues. Temperatures went as high as 80 C though until I turned on Cooler Boost and temps dropped to 62 C.
I guess Turbo + Cooler Boost is the way to go while doing any heavy gaming.
I've moved the default 4.0 GHz Turbo setting to 3.8 GHz as I'll probably be using this setting for heavy games now.