Thanks for the logs and the details included with your reply - this is highly appreciated.
I reviewed them, alongside all crash reports Overwatch was able to upload from your computer over the past few months - and I am sorry to say that this is unfortunately not looking great.
To give a bit of context on this: a “lost rendering device” basically means the video card (or its driver) stopped responding to the operating system and Windows had to re-initialize the card to prevent a full systemic crash. By and large this works pretty reliably, and the computer usually will quickly recover from this, but unless the underlying cause for the device to go unresponsive is resolved things will generally not get better but keep on deteriorating with new (seemingly random) troubles cropping up all over the place, very much like the progression of trouble you’ve been describing from your original post onwards.
With that information in mind: from the data included in the crash-logs it appears the reason for the video card to cease its function was that it suffered from insufficient voltage supply, which indicates that either the power supply unit (PSU) or the motherboard may have trouble (since the card draws power from both components). Voltage issues are of course extremely hard to locate/confirm as it can be excessively tricky to reproduce them thanks to their somewhat random nature - but it would not be unheard of for a PSU to degrade in reliability over time, especially if it may not have been a super-high-end component initially.
If you have the option and don’t mind getting your hands dirty you may want to try using a different PSU (maye you could borrow one from a friend) and see if that improves matters for you - if it does not, or replacing the PSU is not feasible, it’d be time for a local technician to take a look.