GPU's fans randomly revving up to max speed for no reason

[Nutterboy]

Hello,
I have been mining for the last 3 weeks with no issues on my 7870's but today mining anything I have been struck with an issue where my fans alternate from idling speed of ~900rpm to around 95% ~3200rpm
Previous to this the fans have sat comfortably at ~2700-3000rpm and been very stable.

Is this a common thing, is there a cure, what is the issue, and can I fix it?


Thank you for your time.
Any help is appreciated.

[DanielVG]

Which OS are you using?

[Nutterboy]

Windows 7 x64