That’d be the same issue. To go into a little more detail on why we don’t directly support overclocking/XMP, it’s because it’s prone to this sort of instability issue. This doesn’t mean that overclocked hardware will NOT work with our games. I run XMP on my own RAM and it works just fine with all of our games. The problem is that not all RAM is created equal (even two of the same sets of the same model of RAM, which is why it’s important to get matched pairs when building.) You can run into all sorts of issues like not enough voltage, voltage too high, not enough power coming from your PSU, RAM which can’t hold up to its own XMP, a motherboard that can’t handle it or doesn’t support your XMP RAM speed, etc.
My advice? If it’s under warranty, get a replacement set. You may have gotten some lemons. It happens. Even if you do this we can’t guarantee Overwatch will run stably on it, since you may have other hardware issues and overclocking is by nature a hit and miss thing.
There’s nothing engine side which makes overclocking ‘hard-unsupported/guaranteed to crash.’ We just have an engine that’s coded to use as much of your hardware as you let us with the in game settings, which means we’re a good stress test for your overclock setup.
TL;DR - We can’t really help you troubleshoot overclocked hardware, but if the overclock/hardware is fully stable, you shouldn’t have problems. If you’re crashing or having performance issues, try disabling any overclocking you’re doing. If it works, tweak the overclocks or replace defective hardware.