Discussion Prime95 vs. Stock Intel Cooler

[Remeca]

So I've pretty much always run stock coolers, because I don't OC. Never really had issues with overheating (except on laptops.) In another thread here I questioned why everyone is so quick to dump on them. I was challeneged to run Prime95 torture test, and so here are the results (didn't want to keep hijacking the other thread.) So, turns out I was wrong, it was pretty easy for Prime95 to heat up my CPU enough to cook marshmallows. I ran it for about 5 minutes before I conceded defeat. So, I learned something, stock coolers aren't sufficient if you're going to be maxing out all cores for any period of time.

@Karadjgne @remixislandmusic

 

[Karadjgne]

Yes, and as you can see, not only did it hit 100w at turbo speeds in max column, but shortly thereafter dropped vcore and turbo down to base speeds, yet retained the same (roughly) temps, even at an 88w output.

Concepts such as full load and idle can vary from person to person, according to their definition. But really idle is a cpu state below @ 5% and full load is a clean 100% on all cores/threads.

Because of such low outputs, idle temps are very responsive to 2 things, airflow and outside ambient temps. Most cases in most air conditioned areas with decent airflow will generally see cpu temps @ 6-12°C above ambient, which usually works out to around 29-35°C in a 23° ambient (@ 73°F). If idle temps are beyond that, then case temps are running similarly warm, possibly due to insufficient airflow but can be due to inefficient cpu cooling.

Full loads have such extreme wattage output, airflow and case ambient temps take a back seat and cooler efficiency and ability become prime factors. A 110w stock cooler is going to see extreme temps on a cpu with 100w output. To keep temps in check, you'll pretty much need a cpu cooler rated 1.5-2x TDP of the cpu. That puts even budget coolers such as the 140w CM Hyper212 as prime time perfect for stock cpu applications.

Those 92mm/120mm budget coolers have enough physical surface area on the fins to compensate for idle efficiency compared to the stock HSF, but also have the capacity to handle the larger loads. Some get better temps, some get worse, but that's a matter of efficiency in cooler design/fan capability, and not cooler capacity.

 

[LordVile]

So I've pretty much always run stock coolers, because I don't OC. Never really had issues with overheating (except on laptops.) In another thread here I questioned why everyone is so quick to dump on them. I was challeneged to run Prime95 torture test, and so here are the results (didn't want to keep hijacking the other thread.) So, turns out I was wrong, it was pretty easy for Prime95 to heat up my CPU enough to cook marshmallows. I ran it for about 5 minutes before I conceded defeat. So, I learned something, stock coolers aren't sufficient if you're going to be maxing out all cores for any period of time.

@Karadjgne @remixislandmusic

Yeah but it’s not that bad. Suppose a 212 evo is like £15

 

[Karadjgne]

It used to be.


CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£27.95 @ Amazon UK)
CPU Cooler: Cooler Master Hyper 212 RGB Black Edition 57.3 CFM CPU Cooler (£36.20 @ Amazon UK)

 

[Remeca]

Yes, and as you can see, not only did it hit 100w at turbo speeds in max column, but shortly thereafter dropped vcore and turbo down to base speeds, yet retained the same (roughly) temps, even at an 88w output.

Concepts such as full load and idle can vary from person to person, according to their definition. But really idle is a cpu state below @ 5% and full load is a clean 100% on all cores/threads.

Because of such low outputs, idle temps are very responsive to 2 things, airflow and outside ambient temps. Most cases in most air conditioned areas with decent airflow will generally see cpu temps @ 6-12°C above ambient, which usually works out to around 29-35°C in a 23° ambient (@ 73°F). If idle temps are beyond that, then case temps are running similarly warm, possibly due to insufficient airflow but can be due to inefficient cpu cooling.

Full loads have such extreme wattage output, airflow and case ambient temps take a back seat and cooler efficiency and ability become prime factors. A 110w stock cooler is going to see extreme temps on a cpu with 100w output. To keep temps in check, you'll pretty much need a cpu cooler rated 1.5-2x TDP of the cpu. That puts even budget coolers such as the 140w CM Hyper212 as prime time perfect for stock cpu applications.

Those 92mm/120mm budget coolers have enough physical surface area on the fins to compensate for idle efficiency compared to the stock HSF, but also have the capacity to handle the larger loads. Some get better temps, some get worse, but that's a matter of efficiency in cooler design/fan capability, and not cooler capacity.

That's helpful information, thanks. It's been 20 years since I took classes on that stuff so I'm a bit rusty.

Yeah but it’s not that bad. Suppose a 212 evo is like £15

It's the equivalent of £16.65 on my countries Amazon. Probably the first thing I'll get after replacing my 290W PSU.

 

[CompuTronix]

When you ran Prime95, what was your ambient (room) temperature?

Although you ran the latest Prime95 version 29.8, did you use Small FFT's?

Did you disable AVX2 and AVX? (Your i7-4770 doesn't have AVX-512)



CT

 

[Remeca]

When you ran Prime95, what was your ambient (room) temperature?

Although you ran the latest Prime95 version 29.8, did you use Small FFT's?

Did you disable AVX2 and AVX? (Your i7-4770 doesn't have AVX-512)



CT

I ran Small FTT s on default settings as instructed. Does disabling AVX make a difference if my CPU doesn't support it?

 

[CompuTronix]

I actually stated "(Your i7-4770 doesn't have AVX-512)"

See the check box for AVX2?

When you click on it, AVX2 will then be disabled, which will in turn allow you to also disable AVX.

Advanced Vector Extension (AVX) Instruction Sets were introduced with Core i 2nd Generation CPU’s, then AVX2 with 4th Generation and AVX-512 with later Generations of High End Desktop (HEDT) CPU’s as in certain X-Series, Extreme, i9’s and i7’s. Prime95 versions with AVX enabled impose an unrealistic 130% workload which can adversely affect stability and severely overload your CPU. 2nd and 3rd Generations are less affected, but Core temperatures on 4th through 9th Generations may be over 20°C higher.

Many 6th through 9th Generation motherboards address the AVX problem by providing “offset” adjustments (downclock) in BIOS. -3 (300 MHz) or more may be needed to limit Core temperatures to 85°C. Since 4th and 5th Generations don’t have AVX offsets, you can create individual BIOS Profiles for AVX and non-AVX software. Except for a few utilities and specialized computational apps, real-world apps (rendering / transcoding) with AVX and recent games with AVX shouldn’t exceed Prime95's workload without AVX.

As per Intel’s Datasheets, TDP and Thermal Specifications are validated “without AVX”. In Prime95 versions from 27.7 through 29.4, AVX can be disabled by inserting CpuSupportsAVX=0 into the local.txt file, which appears in Prime95's folder after the first run. However, since Core temperatures will be the same as 29.8 without AVX, it's easier to just use 29.8. You can also use 26.6 which doesn't have AVX. Core i 1st Generation, Core 2, Pentium and Celeron processors don't have AVX Instruction Sets, so they're not affected.

Please re-run Prime95 Small FFT's with AVX2 and AVX test selections disabled.

CT

 

[Remeca]

I'll run it again with AVX disabled, but I suspect the results will be similar. After a few minutes I'll hit 90C and stop the test. So Small FFT s, disable AVX, AVX2, AVX-512 checked?

 

[CompuTronix]

AVX-512 is greyed out because your processor does not have the AVX-512 Instruction Set. Please disable AVX2, then AVX in that order.

Your power consumption (watts) should be closer to the processor's rated TDP, which is 84 watts, while the clock speed should remain stable at 3.9GHz. Your Core temperatures should be significantly lower.

CT

 

[Remeca]

It was certainly a different result than before, although clock speeds immediately dropped to base speeds when I started the test, then went back up when I stopped it.

Before:

During:

After:

Temps stabilized by 4 minutes into the test, so I stopped it. Ambient temp in the room is 23C.

 

[CompuTronix]

The test you just performed is valid, as it conforms to Intel's Datasheets. Your Core temperatures are OK on the stock cooler.

Although Throttle temperature (Tj Max) for your i7-4770 is 100°C, it’s not advisable to run your CPU near it's thermal limit. If your hottest Core is near it's specified Tj Max Throttle temperature, then your CPU is already too hot.

The consensus among well informed and highly experienced system builders, is that cooler is better for ultimate stability, performance and longevity. Experts all agree that it's prudent to observe a reasonable thermal margin below Throttle temperature. Accordingly, here's the nominal operating range for Core temperature:

Core temperatures above 85°C are not recommended

Core temperatures below 80°C are ideal.



We actually have a guide for this topic in the CPUs Forum that you might want to read: Intel Temperature Guide - https://forums.tomshardware.com/threads/intel-temperature-guide.1488337/

CT

 

[Remeca]

Thanks for your input! Lots of good information on here, I'll have a better idea what to look for when I get a new cooler. My room's ambient temperatures can go above 30 in the summer, so a new cooler isn't a bad idea. My main goal is longevity, so an aftermarket cooler is probably a good idea.