Question CPU cooler vs thermal paste problem

[digitalio]

I've applied new thermal paste to my CPU cooler (i7-4790k, Arctic MX4, CoolerMaster 120mm water cooler) as it was old and my CPU was heating to ~43C in idle mode and now getting 31/30/29/26C; however, when I run a torture test the temperature gets all the way up to 99C, what is uncool.
I wonder if this is a sign that I didn't apply the paste properly?

 

[NightHawkRMX]

How old is this liquid cooler. After 2-5 years depending on quality the pumps can fail causing this

 

[digitalio]

As old as the PC itself. About 4 years.

 

[jamesanyoung]

I just replaced my 5 year old AIO cooler for this reason. CPU would spike and thermal throttle. Get a new cooler, clean off the old thermal paste with some 99% ISO and put on the new cooler.

Most people on this forum will recommend a good air cooler, like the Noctua

 

[Karadjgne]

What torture test? If using Prime95 with that cpu then it needs to be v26.6 small fft. Any version after that uses AVX (and a few others) which will drive the cpu to @ 130% supposed loads andvseriously unrealistic temps. Since games don't use AVX or AVX2 or FMA3 or AVX512, then having them run in a torture test is counter productive.
26.6 small fft gives a 100% consistent load thats equitable to what you'd get running games.

If you ran Prime95 29.4 and got 99°C, then you'd be looking at closer to 70ish°C with 26.6, at a more accurate gaming max temp.

 

[digitalio]

That sounds like too much hassle for now. I undervolted it a bit, this seems to have solved the problem. Never gets above 90.
By the way, why air cooler? I just don't like them because they block access to all the slots on the motherboard.

 

[digitalio]

What torture test? If using Prime95 with that cpu then it needs to be v26.6 small fft. Any version after that uses AVX (and a few others) which will drive the cpu to @ 130% supposed loads andvseriously unrealistic temps. Since games don't use AVX or AVX2 or FMA3 or AVX512, then having them run in a torture test is counter productive.
26.6 small fft gives a 100% consistent load thats equitable to what you'd get running games.

That's interesting. So, with v26.6 I'm getting 76C max. Sounds good enough for me.

 

[NightHawkRMX]

Thats safe and good.

 

[NightHawkRMX]

Air coolers rarily ever go bad, unlike liquid cooling that has a short lifetime untill it eventually fails. I would replace the aio anyhow with that age. I have seen aging aios leak suddenly and kill motherboards and gpus. I also have seen aio pumps fail and cause unexpected overheating and shutdowns. Air coolers never have this troble if kept dust free.