One day when I cleaned my Old Computer. Which wasn't clean from a year.
I found that the Gap between the CPU Fan and Processor was filled by Alot of dust and Webs of spider.
I cleaned it and then found this big margin:
Idle Temp: 54
Full load Temp: 65
Idle Temp: 39
Full load Temp: 57
So I'd say that you should clean your GPU with a Blower.
If you cleaned properly and then also nothing decreased then send it to RMA.