I7 4790K - 30 at idle, 80 under full load

[Bondarev]

Hey guys,

About a week ago I ran a test with Prime95, CPU kept under 60 degrees Celsius.
I am using a Corsair H110 watercooler.
However, the fans were making some noise so I put some shims between the case and the fans, and the radiator and the case.
Now when I run Prime95, my CPU shoots up to 80 degrees.
Could this be caused by those shims?
It runs at 30 degrees when idle, not overclocked.

Thanks in advance!

 

[Shneiky]

All prime95 versions above 26.6 cause Haswell chips to heat up rapidly. Download Prime95 26 or lower and try again.

 

[Bondarev]

The very weird thing is that a week ago I used the newest version and got 60 degrees, now I'm using the newest version and get 80.
If I use a version 26 or lower I get 60 again, pretty confusing..

 

[Shneiky]

Prime95 versions 26.6 and up put a load on the FP (floating point) units on the CPU. Since Haswell has been known to have high thermal density and a TIM instead of soldered between the cores and the heatspreader - heat rises rapidly. This condition is not about how much heat your cooler can take off - it is about how fast it can take out the heat. But the TIM in the Haswell CPUs is the "bottle neck" of heat transfer so the heat is trapped close to the cores because it can't reach the heatspreader fast enough.

This is not a Prime95 issue - it is a known Haswell design.

 

[mahanddeem]

What I did to reduce my 4790k temp was to experiment with lower voltages than stock ones. Ended with manual 1.15v for 4.4ghz oc. That reduced my temp almost 10c on hottest core. Maybe my cpu is good but worths a shot if you experience high temp.