My CPU runs at 55 degrees Celsius while idling? Why did it get so hot all of the sudden?

[Thesignificantbit]

I built this pc about 5 months ago, and it has been running fine. I have an i7 intel processor with the stock fan mounted on it. When I first built the computer, it's idle was around 35 degrees Celsius. Ever since yesterday it idles around 55 degrees Celisus, which is way too hot. It is definitely affecting the performance of my computer because when I open a program, it can get up to high 60s and low 70s. Any idea what is going on, and why it would suddenly do this?

 

[flank2]

maybe the hsf failed or maybe the heatsink is clogged with dust? idk, open up your case a take a look

 

[clutchc]

Check for dust buildup in the cooler and fan. Also check the intake & exhaust fans for same.

It's possible one of the push-pin feet on the stock cooler came loose. Check the backside of the MB to see if the black posts are fully spreading the white feet securely behind the board.

It seems a bit early to have to change the thermal paste, but if it comes to that, clean it from both cooler and CPU. Then replace with something like MX-4.
http://www.newegg.com/Product/Product.aspx?Item=N82E16835100010
http://www.newegg.com/Product/Product.aspx?Item=N82E16835186038

 

[Spaniard United]

CPU could need new paste
CPU heatsink could need to be dusted
Check your fans and make sure none of them stop working

Also, for the record, stock heatsink is weak. You can pick up a very good air cooler for $25-$35 (Cooler Master Hyper 212).

 

[Thesignificantbit]

CPU could need new paste
CPU heatsink could need to be dusted
Check your fans and make sure none of them stop working

Also, for the record, stock heatsink is weak. You can pick up a very good air cooler for $25-$35 (Cooler Master Hyper 212).

I am an idiot. I forgot to mention. My fan is running fine. The BIOS says it is running at 2000 rpm.

 

[Thesignificantbit]

Hey guys thank you for your help. One of the legs on the stock intel cooler isn't locking, so it looks like I will have to go buy another cooler. I got it to attach pretty well, and now it is back down to 35 degrees celisus when it idles. However, since the leg is broken, it will probably happen again. Thanks for the help.