GTX 970 running at 80°C playing ARMA3 on singleplayer

I recently bought a ZOTAC GeForce GTX 970 but the GPU has been running at very high temperatures especially during gameplay. So far I've mostly been playing ARMA3 as it was one of the main reasons I purchased the card. I first tried playing the game on Ultra and on the surface the card preforms well as I have no FPS lag and the game looks beautiful but not long into gameplay the card quickly raised in temperature to 80°C and I could smell very faint burning. In an attempt to lower this I thought running the game at Very High may solve the temperature issues so I closed ARMA3, waited for the GPU to cool down and than tried running the game at Very High but still encountered the same problem. I then tried the same approach at High and Standard and the temperature still goes to 80°C.

My Hardware Specs:

• Motherboard: ASUS Sabertooth Z97 Mark 2
• CPU: Intel Core i5-4690K
• GPU: ZOTAC GeForce GTX 970 4GB
• Memory: 2 x 4GB DDR3 @ 1866Mhz

My CPU is also running on air using the stock cooler and my case has two 120mm Chassis fans, one placed at the front and the other at the back.

I want to know whether the GPU is defective or is this normal behavior for my hardware. I know ARMA3 is a very demanding game and is very poor for benchmarking hardware but to my knowledge I should at least be able to play this game on Standard at a reasonable temperature.

Thanks in advance.