Question Help with Thermalright Peerless Assassin overclocking please ?

[sambaniamerian]

Hello,

I have an 8700k with a brand new Thermalright Peerless Assassin. It has 4 120mm fans on it. 3 fans directly and one right beside it on the case exhaust. They're all blowing air the same direction through the cooler.

The case does sit under my desk but these results are extremely disappointing !

I had my 8700k previously set for 1.376V max as indicated on hw monitor trying to go for 5ghz, it hit 84-85C on cpuz stress test. My chip seems like a bit of a turd so I dialed it back down to 1.32V(4.8GHz) a 0.05+ reduction and I was expecting a 6-10C drop. However under the same test its running 79-81C. Only 3-4C cooler than with 1.376V !

I see reviews with 200w normalized and this cooler with fewer fans getting 60c results. How come my 8700k is running 80C with this supposed best air cooler at 1.32V.

TLDR, I replaced a leaky fractal liquid cooler, dialed the voltage down 1.376V to 1.32V and temps went from 84-85 to 79-81C. How come it's running so hot, I'm quite sure it was tightly mounted. I am using older arctic 5 paste but shouldn't it be like 60C not 80C.

CPU is not delidded. Ambient temps are decent, February in Canada with window open. Room can't be more than 20C.

Thank you.

 

[Ralston18]

This:

"They're all blowing air the same direction through the cooler."

Perhaps - maybe too much air and the end is a balloon effect that actually limits airflow.

Two suggestions:

1) Update your post to include full system hardware specs and OS information.

2) Take two or three photographs of the case showing all fans and air flow directions. Post the photographs here via imgur (www.imgur.com).

Another consideration is expectations: for example is "3-4C cooler" in or out of some margin of error?

What about voltages to 3 decimal places.....?

 

[geofelt]

First of all, I do not see your temps as alarming.
The processor should be happy enough up to the 100c. throttle point.

The cooler was designed for two fans; adding another is not likely to help much and could possibly hurt.
Try testing with only the two stock fans.

The rear case fan should be an exhaust to get hot air OUT of the case.
You description suggests you have it blowing through the cooler. Don't know how that might work.

Any cooler needs a good source of fresh air to let it do it's job.
What is the make/model of your case, and what is the fan arrangement?
What is your graphics card?

 

[sambaniamerian]

Hello, thanks for the quick replies.

Z370 Asus prime motherboard.
8700K was at 1.376V vcore 84-85c 100% load cpuz stress test, only dropped to 78-80C at substantially lower 1.30v vcore(lowered it again from 1.32V). Using peerless assassin and 4x 120mm fans as listed.

The temp tests were done back to back within 15minutes on cpuz stress test and HW monitor.

Windows 11
DDR4 3000MHz OC (old sticks)
Corsair 850w PSU
3080ti ftw3 ultra


There isn't much space near the back of the case so I thought to point all of the fans in one direction to blow out of the front of the case. I removed the covers for the optical drives so there is a wide open hole the width of the cooler in the front of the case. I can feel substantial air blowing through it.

There are two fractal fans from the old AIO cooler, and two thermalrite fans blowing on the fin stack. There is one bequiet fan blowing bottom up towards the GPU.

Thanks again for your help, here are the photos.

https://imgur.com/a/UdjJEtU

View: https://imgur.com/a/UdjJEtU

 

[geofelt]

Good... Your picture is worth a thousand words.

I think your setup is a mistake.
Direct all the cooler fans to blow through the cooler and OUT the back of the case.
You want to get heat OUT of the case ASAP.

I think the front fan is not needed. see if things work as well without it.

As a plus, you will not be getting hot air on your face or legs from the front of the case.

 

[sambaniamerian]

Good... Your picture is worth a thousand words.

I think your setup is a mistake.
Direct all the cooler fans to blow through the cooler and OUT the back of the case.
You want to get heat OUT of the case ASAP.

I think the front fan is not needed. see if things work as well without it.

As a plus, you will not be getting hot air on your face or legs from the front of the case.

Hey geofelt, thanks for the reply.

The reason I chose to direct the fans to blow towards the front is because there isn't much space between the case and the table. I removed the covers for all of the optical drive slots to allow for a big opening to blow air through. It's a bit visible in the photos.

I checked the temps with 1.3V and 4.8GHz and it's fine I suppose, 78-79C 100% load, 35-39C idle. The results I saw were 50-58C but I didn't realize it was above ambient I thought I should be getting high 50s or low 60s C.

I suppose if I brought the case out from under the desk it would drop a bit more too.

My main concern was that I dropped it from 1.376V to 1.3V and it seemed to me the temperature drop wasn't commiserate with the voltage drop, 84-85c to 78-79c, 6C difference for what seemed to me a large voltage drop.

I was more worried that I had mounted something incorrectly and that the temperatures should be much lower than they are, because I didn't understand why the temperatures were still near 80C with this top performing air cooler and multiple fans.

Also the cpu doesn't like anything over 4.8GHz. It required at least 1.35V for 4.9Ghz and over 1.4V for 5GHz. However I did find that it was happy at 1.3V and 4.8GHz.

I'm mostly holding out for 8800X3D, even at 4.8GHz the 8700K and 3GHz ram do bottleneck me in certain games.

So what are some of these people and reviews saying they get 50-60C max on heavily OC 200w+ CPUs ? Are they just mistaken or lying ? If the top of the line air cooler can only manage near 80C on 8700k 1.3V how are people getting under 60C with more demanding CPUs ?

Sorry for the long winded reply !

 

[geofelt]

Intel chips are designed to tolerate 100c.
If your main use is gaming, you are only going to stress one or two threads so occasionally touching 100c is ok.
What should happen is that the processor will just slow down for a bit.

Your photos show that there is a gap of about 4" behind the rear of the case. That is plenty to let hot air escape the case.
I would give it a try.

If you are running ram at xmp 3000 speed, reset it to stock.
There is an interaction between ram voltage and overclocking.
With ram at stock, you should be able to oc the cpu higher.
Intel is not sensitive to ram speed for performance, so you should net out better.