Radeon R9 280 acts weird

[DerBurner]

My Sapphire Radeon R9 280 has started dping really strange things lately, when I´m playing games like Crysis 3 or Battlefield, mostly any game, she reaches 100% utilization after 2 to 3 minutes and stays at this point. At the same time she throttles to 500Mhz (boost clock 965 Mhz). This results in unplayable framerates. 
I recognized it for the first time when i got my new full hd monitor a few days ago. My old monitor had a 1680x1050 resolution (i´m still using it as a secondary monitor). When im playing games at the old 1680x1050 monitor the same things are happening, but the 500 Mhz can hold the frames at playable rates on the old monitor. 
I never experienced this before, i got my pc a year ago and did some testing before, where everything seemed OK. 
Im using MSI Afterburner to monitor temps, utilization and clock speed. 

My system:

Intel Core i5 4570
Sapphire Radeon R9 280 (rebranded HD 7950)
Corsair Vengeance 8gb RAM
Windows 8.1

 

Of course I thougt about temps, i set the fans at 50% and the average temperatures are at 50 to 60 degrees, which is not to high.

 

Thanks for all helpful answers!

[killcomic]

Yeah, AMD Powerplay strikes again.

My 280 did the same. I installed Afterburner, disabled Powerplay and overclocked it to boot. No more downclocks after that.

[AnnoyedShelf]

Yeah, AMD Powerplay strikes again.

My 280 did the same. I installed Afterburner, disabled Powerplay and overclocked it to boot. No more downclocks after that.

Ironically, power play on laptops works as intended

[killcomic]

Ironically, power play on laptops works as intended

I think some 7950's/R9 280's had issues with it. Life in the red team.

[don_svetlio]

Could it be heating up?

EDIT: Nevermind, 50-60 is perfectly fine. Power play is the culprit.

[DerBurner]

Yeah, AMD Powerplay strikes again.

My 280 did the same. I installed Afterburner, disabled Powerplay and overclocked it to boot. No more downclocks after that.

Do you now how to disable Powerplay? I disabled ULPS (Ultra-Low-Power-State) Mode in AFterburner, still same clock speed.

[killcomic]

Do you now how to disable Powerplay? I disabled ULPS (Ultra-Low-Power-State) Mode in AFterburner, still same clock speed.

There is a section that you can choose under setting --> General then down the bottom there is something about unofficial overclocking mode. There you can select 'without Powerplay'.

 

I'm going off memory here as I'm at work ATM. But that's the gist of it.