Build Advice PC idling at 70+ degrees

[treacle69]

I've been having problems with heat warnings for awhile, after doing an update my PC stopped working so I had to re-install windows and start from scratch. On a clean slate my PC was idling at 70 with the CPU fan on full speed. I applied some thermal paste and cleaned the fans, which was long overdue, to no avail. My PC was built 5/6 years ago when i was 15 by computer planet and it's fair to say I made many mistakes on the components. I moved and inverted the small 8cm fan from the side of the case to the back to try and improve airflow. This seemed to do the trick, the PC would now idle at 60, still not ideal but a clear improvement. However, starting the computer today and it went straight up to 70+. I put it to sleep and cameback later and the temperature had dropped again back to 60. It seems that it only overheats when starting up from shutdown, I will test this straight after I have posted this. This is all while the GPU fans are on auto (0%). Putting the fans to 100% can hold the temp in the high 60's, but gets very loud and isn't suitable for idle conditions.

What I want to know is, why the PC doesn't overheat when waking up from sleep? And what would be best to invest in immediately considering money is tight for the rest of the year (New case/case fans, CPU heatsink/fan etc.)?

I also read something about 'burning in' thermal paste, which sounds relevant as well.

5yr old Build:

Case: CiT Mars Midi Tower Part-Mesh Gaming Case with 2x Red LED Fans and LED Display https://www.amazon.co.uk/CiT-Tower-Part-Mesh-Gaming-Display/dp/B006FUQ34Q
PSU: Evga Supernova 650 G2 (2 yrs old)
Mb: Gigabyte 78lmt-usb3
CPU: Fx-8320 3.5GHz (Stock)
Heatsink: Stock
RAM: 16GB DDR3
HDD: Seagate Barracuda 1TB
GPU: RX 480 8GB (2 yrs old)
OS: Windows 7 (x64 bit)

 

[rascalov]

Change the stock cooler with aftermarket one. Put good thermal paste using the line method.

 

[treacle69]

I am looking at buying the BE QUIET Pure Rock Slim 92 mm CPU Cooler, it has good reviews and my case means I need a cooler <14.5cm. I have found out that my current cooler is Xigmatek TYR SD962B.

I do not have the money to spend a lot at the moment, but I hope the Be Quiet will be suffiecient.