Benx

Lol. I bought a phanteks halo for the front and did some custom stuff with the noctua heatsink cover, Plexiglass, and a XSPC sing rgb LED . I am pretty happy with the result, let me know what you think. Oh and the heat sink is the chromax u12s.

It does matter, different brands have different coolers, when there is a difference in price it is typically due to cooler quality. A worse cooler could mean worse performance, also different manufactures use different parts that can effect performance. I'm not as familiar with nvidia, but in amd gpus different manufactures can use different vram. With that in mind top manufactures do have better rma policies as stated above. 

I agree to a point, but cpu's degrade over time. Overclocks stable when new might become unstable a couple years down the road, so it is possible the cpu could be going. However if you haven't already repasting the cpu and reseating the heat sink is always a good first step to see if a new cpu is necessary 

Honestly with the 1600AF out there, AM3+ is very dead.
Don't even bother. Get a 1600AF, 8 Gigs if you want to keep it very cheap and a very basic board and you are good to go.

it will be absolutely fine.

Thanks your a legend.

It might be a bad power supply or mobo. Do you have an extra power supply to try?