I bought my pc in the last year and since then i have a big problem with my gpu. when i play games, the temperature go up to 80 degrees and i've set its fans to run on 80% on this temperature. my case is small (480mm x 200mm x 460mm) and it has 3 fans. according to this review my video card must not go over 60 degrees when i'm gaming: http://www.guru3d.com/articles_pages/galax_geforce_gtx_970_exoc_review,8.html
my case (it's very small):
if i set the gpu fans to 80% on any temperature, the temperature doesn't increase any more for example if i set the fans to 80% on 60 degrees, the temperature stays 60 C in heavy games.
if i set fan speed to auto the temperature goes up to 90 degrees !
does setting fan speed that high (80%) affect fans lifespan? if the fans stop working is there any way to change them? if i get a biger case, does gpu temperature decrease?
my case (it's very small):

if i set the gpu fans to 80% on any temperature, the temperature doesn't increase any more for example if i set the fans to 80% on 60 degrees, the temperature stays 60 C in heavy games.
if i set fan speed to auto the temperature goes up to 90 degrees !
does setting fan speed that high (80%) affect fans lifespan? if the fans stop working is there any way to change them? if i get a biger case, does gpu temperature decrease?