iMac 27 late 2013 temperatures after upgrading from i5 to i7

[venique]

Hi there!

I've upgraded iMac 27 late 2013 (iMac14,2 - A1419)

from
- i5 4570 3.2GHz
- 8GB RAM
- 755M 1GB
- 1TB HDD
- latest macOS Catalina
- stock thermal interface and about 5 years without any dust removing

to
- i7 4771 3.5GHz
- 32GB RAM
- SATA 1TB Samsung 870 EVO
- NVMe 1TB Samsung 970 EVO Plus + Sintech adapter + flat aluminium radiator
- new thermal interface (MX-4 at CPU and GPU + Gelid 1mm thermal pads at GPU VRAM)
- macOS Ventura via OCLP

It feels like new machine that will be good enough for web and audio for few more years I hope. But I get worried about temperatures. There is some tests (sorry for photos instead of screenshots):

idle before (fan @ 1200 RPM)


idle after (fan @ 1200 RPM)


full load before (fan @ 1900 RPM)


full load after (fan @ 2650 RPM)


As you can see, idle temperatures are similar. With full load GPU/CPU temperatures mostly are the same but 1st CPU core always about 100C, fan at full blast instead of 2k RPM with i5 and I've noticed thermal throttling - after about 1 hour of FurMark+CPU Burner it goes to 2.7GHz. After some cool down and running only CPU Burner it keeps stock 3.5GHz for about 1-2 minutes and then goes to 3.3-3.4GHz.

Yes, i7 definetly hotter that i5. Yes, even modern iMacs with i7/i9 have thermal throttling. But I've replaced all thermal interfaces and did very deep cleaning. So even after that I'm hearing fan very often. Not every time, because while browsing (for example - single 4k video at Safari) i get CPU temp at 60-70 and GPU at 45, while fan start speeding only when CPU goes over 90 degrees.

Is it normal temperatures?

Why I'm worried about:
- Instead of brand new MX-5 I've forced to use about 5 yo MX-4 (internet says that MX-4 can last for 8 years) because it seems that MX-5 was defective (it was solid as .... and I can't apply it properly).
- While assembling CPU and cooling system (hardest part when you need to flip it over) I only succeeded to mount two left screws at CPU backplate, other two holes didn't matches each other so I had to rotate cooling system for about 1-2 degrees so all holes got matched and I got chance to mount last two screws. And I'm afraid that while rotating the cooling system it could wipe off some thermal paste from CPU/GPU or thermal pads can get off from VRM.

Thanks in advance.

 

[Nguyen Duc Hieu]

Your temperature readings look normal for me.
It's a hot CPU inside an ill-ventilated case.
In another post of this forum, people had tried to widen the top ventilating crack and got good results.
As far as I remember, that DIYer milled out the crack to 1/2 inch wide.

 

[venique]

Thank you. Can you please link that post? I didn't find it and wondering how it possible with it's full metal body.

 

[Nguyen Duc Hieu]

Thank you. Can you please link that post? I didn't find it and wondering how it possible with it's full metal body.

You do have to drill or mill the top part of the aluminum body.
But maybe it's not possible for you. Need a lot of guts to do such modifications.