GPU lifetime deterioration

Hi,

I've recently got into mining and therefore put my GPU (7870) under a fair amount of usage. I mine at fairly low intensities (12 on cgminer) and occasional higher intensities for a maximum of 8 hours at a time. During this time the temperatures hit a maximum of 64 Celsius. I know this isn't a temperature to panic about but I was wandering how this would affect the longevity of the GPU.

Also I was wandering what takes it's toll on the GPU's lifetime, usage or temperature (I'm not talking extreme temperatures, more like ~60).

any temperature that is under the TDP of the card will improve the lifetime, but likewise heavy usage of the card like so in mining will also drastically reduce its lifetime. if you are taking good care of it and dusting it and keeping the temperatures down then you should be fine for a while, i cant tell you how long it will last though, you will probably be good for a few more years even with heavy mining loads and gaming.