iMac 5K - 4790K, M295X - thermal compound + second SSD upgrade + Air Vents MOD

AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
Hi all!
It was a pleasure to find this forum beginning of this year. I have iMac 5K with i7-4790K and m295X.
After almost 2y of using this desktop, I stuck with unusual high temperatures for CPU and GPU.
Idling with Chrome and YouTube, EyeTV, CPU was around 70 up to 102'C while gaming on Windows 10.
GPU idling around 90 up to 105'C under heavy load on Windows (GTA V).
It took me a over a month to figure out it must be old stock thermal compound or lots of dust.

Well... It was both!

This is what I found after opening iMac:


1y 10m of using an iMac 5K we have this stuck on the fan:


Stock thermal compound, was really dry. It looked and break like old fragile plaster :(


CPU with stock compound


GPU and SDRAM with stock thermal compound


After cleaning with ArctiCleaner 1/2 and new GC-EXTREME compound. I used almost whole GC-Extreme 10g Thermal Compound (TC-GC-03-10g)


On IFIXIT website they advice to stick this at the back to level the motherboard. But this is not necessary, as there are some level points at the back of the board and case.


All stuck together with second SSD Crucial MX300 750GB. Spare for data.


I did NOT peel off the adhesive tape on the top and each side, so only the bottom adhesive is holding the LCD to the iMac. I used four strips of adhesive transparent tape to temporarily hold the screen to the frame. Just in case something will go wrong in next couple of days.



New stuff I bought for this job:

1. iMac Opening Wheel Nylon Handle Complete Tool
2. 2x Plastic Cards
3. iMac Intel 27" EMC 2546 and EMC 2639 Adhesive Strips Strips only - 1 qty.
4. iMac Intel 27" 5K Late 2014 and Mid 2015 Hard Drive Cable IF174-006-1
5. OWC OWCDIDIMacHDD12 In-Line Digital Thermal Sensor for 27-Inch iMac 2012
6. I had old 2.5" drive bracket from OCZ and spare Crucial MX300 750GB as a second drive for data

- temperatures - After (left) - Before (right)


At the end I would like to thank tubeexperience for help and answering my questions!
 
Last edited:

steve23094

macrumors 68030
Apr 23, 2013
2,709
1,489
You mention max temps when gaming under Windows before you cleaned out and applied new thermal compound. What are the max temps you get under high load now?
 

AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
What are the max temps you get under high load now?
Hi, now I have a fresh Windows 10 with BETA Driver Packaging Version 15.301.2101-160209a-299468C, playing GTA V 1.0.877.1 average is 85'C. Sometimes it can get up to 98'C but then fan will go mental and temp is quickly down to around 84-88 ;)

What I noticed is how quiet iMac 5K can be. Before even just watching a YouTube video makes fan go crazy, up to 1800-2100rpm.

15min playing GTA V
 
Last edited:

EnderBeta

macrumors 6502a
Aug 5, 2016
567
521
You have the exact same iMac as me. If it wasn't for Apple Care I would love to do this same procedure, great work!

Do you mind doing this 8 minute video image retention test here:

https://forums.macrumors.com/threads/could-anyone-with-a-5k-imac-please-do-this-test-for-me.2027201/

I am curious to see if your identical iMac to mine has the same issue.
Do you think you could point out the poor cooling and solution to have AppleCare do preventative fixes on the hardware?
 

macmee

Suspended
Dec 13, 2008
835
1,105
Canada
Do you think you could point out the poor cooling and solution to have AppleCare do preventative fixes on the hardware?
I was just going to ask, I wonder if I can ask the repair guys to slap some new thermal paste on everything, i will check
 

dotnet

macrumors 65816
Apr 10, 2015
1,187
854
Sydney, Australia
I have no doubt that new thermal paste, properly applied, and a clean fan will improve the situation. A big part of the improvement you're seeing isn't real, though, but due to different loads during the before and after tests:



Everything will obviously run cooler when the CPU uses only a third of the power, and the GPU 23% less. That's an extra 30W you didn't burn when you took the post-upgrade figures.
 

mikeboss

macrumors 65816
Aug 13, 2009
1,295
478
switzerland
you applied a ridiculous amount of thermal paste. WAY too much!!!

EDIT
and yes, just as "dotnet" mentioned: the before and after temps are totally useless if the CPU consumes three times the power during the "before" readings...
 
Last edited:
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AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
Hi,
Maybe this will help, I'm watching 2 YouTube Videos - one to check burn of CNN on LCD, other in HD 720 to put some load on CPU. Fan is still on ~1202rpm. Temps and load below.

This is what I got:


I can confirm temperature is much lower with new thermal compound and clean fan :D


After 8min I don't see any CNN on my screen, but after 40min on Windows, than back to macOS I have this:


 
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macmee

Suspended
Dec 13, 2008
835
1,105
Canada
Hi,
Maybe this will help, I'm watching 2 YouTube Videos - one to check burn of CNN on LCD, other in HD 720 to put some load on CPU. Fan is still on ~1202rpm. Temps and load below.

This is what I got:


I can confirm temperature is much lower with new thermal compound and clean fan :D


After 8min I don't see any CNN on my screen, but after 40min on Windows, than back to macOS I have this:
Thanks so much for doing that test for me man, I appreciate it.

It's crazy...... that retention have is even in the same spot as where it appears on mine, on the right side!
 

AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
Hi,
I hope you all had a blessed Christmas!

It's almost a year after I done some work on my iMac 5K. So today I manage to do a surgery upgrade on cool air inlets and hot air outlets.

Tools:
14.4V Makita Drill
2mm + 6.5mm Kendo HSS Drill Bits
250ml Isopropyl Alcohol
1000 + 1500 Sand Paper


29 + 21 Cool Air Inlet Holes, Total 50 x 6.5mm Holes


Instead of 18 narrow Hot Air Outlet Holes I manage to cut down 8 bars, for 4x2 big outlets.




After this surgery what I noticed is that this single fan on iMac 5K during a game is not always on full speed.
Looks like there is a lot of air going in and out, which probably is helping a bit to cool down i7 4790k and R9 X295M. SSD is cooler a bit too ;)



Now my iMac 5K late 2014 looks almost like iMac Pro :D
Happy New Year!!
 

AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
Hi, hope you all well.
I am getting ready today to get my 4790K delid and lower temps with Thermal Grizzly Conductonaut.
As my temps at idling are still acceptable, when trying to edit 4K video, core temps reaching easily 98'C.
So will keep you posted ;)
 
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Malus120

macrumors 6502
Jun 28, 2002
313
367
Hi, hope you all well.
I am getting ready today to get my 4790K delid and lower temps with Thermal Grizzly Conductonaut.
As my temps at idling are still acceptable, when trying to edit 4K video, core temps reaching easily 98'C.
So will keep you posted ;)
As a former 2014 RiMac 4690K/M295X owner I salute you. The DIY work is awesome, and now you're going to delid the CPU!? You sir are a boss :D Makes me wish I still had mine :(
(Not that I'd have the guts to take it apart)
 

AlexMaximus

macrumors 6502a
Aug 15, 2006
914
281
A400M Base
Hi, hope you all well.
I am getting ready today to get my 4790K delid and lower temps with Thermal Grizzly Conductonaut.
As my temps at idling are still acceptable, when trying to edit 4K video, core temps reaching easily 98'C.
So will keep you posted ;)
Thank you so much for your pictures. Impressive work, and kudos for the DIY cooling mod.
It really surprises me that the iMac is getting clocked up that quickly. I really love the 5K screen and would love to get one in the future. Now here is a good question for you:

Since the black iMac Pro body has the same chassis and overall frame size, would it be possible to get the dual fan from the iMac Pro unit and install it on your machine, assuming the power plug could be modified or the same one is used. That would be awsome, because that would mean any standard iMac 5K could be modified using a dual fan iMac Pro module. I would be in PIMP Heaven if that would work ....
 

AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
Thank you!

Regarding upgrading fan in 2014/2015 iMac 5K and changing it to dual fan from iMac Pro, it wont be possible. This two fans are slightly slimmer, but they taking much more space inside. They have 6 pin connector instead of 4pins in iMac 5K 2014/15.

But there is a chance to fix/glue/weld two fans from iMac 2014 into one. Only disadvantage will be taking off HDD bracket out. Like here:

Here you have this two iMacs side-by-side:
So its possible ;)
[doublepost=1525738613][/doublepost]Update III: Delid & Relid of i7 4790K

Disassembly of my iMac took me around 25min ;)
I met really nice local guy in London - uk-delid - with cheap auction on eBay - DELID & RELID service UK - Intel CPUs (Coffee lake, Kaby lake, Skylake, Haswell)
Thank you for you great job!

Process took only 45min.




But now, CPU is idling between 45-50c and reaching max 93c when in stress before fan kick's-in to lower temps to 80-85c.

GTA 5 - 15min in game - not even once throttling below 4GHz ;)

Youtube and EyeTV - 1h video and TV

Ended with total difference around 25c lower!!! But the best thing is, CPU won't thermal throttle to get lower
frequency and therefore lower temperature, like it was doing before while processing 4K video in iMovie.

Thank you Intel(R) for low-quality toothpaste on my CPU!
 
Last edited:

Glmnet1

macrumors 6502a
Oct 21, 2017
953
1,054
These intrusive operations are obviously not routine but I’m wondering, what do you guys do with your iMac to prevent that kind of dust to accumulate? Just shoot air through the holes? Is there any kind of filter installed to prevent that on such a closed system? I clean my 2011 MBP at least once a year and plan to buy an iMac soon.
 

AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
You can shoot air through air vents, but this won't reach fan. You can see what is on my fan after first opening:

I did really very often clean vents with compressed air. This make air vents clean, but fan stayed blocked with dust. This iMac should be fitted from factory with a way to easily open the case for cleaning.

But like my new friend from eBay said - Apple or Intel - want you to buy new stuff every 2-3 years. So...
 

Glmnet1

macrumors 6502a
Oct 21, 2017
953
1,054
You can shoot air through air vents, but this won't reach fan. You can see what is on my fan after first opening:

I did really very often clean vents with compressed air. This make air vents clean, but fan stayed blocked with dust. This iMac should be fitted from factory with a way to easily open the case for cleaning.

But like my new friend from eBay said - Apple or Intel - want you to buy new stuff every 2-3 years. So...
I see, thank you. Good job on the maintenance btw, it’s always nice to see someone extending the life of their device!

Did anyone tried to install air filter on it? With Apple Care, can you get it cleaned at an Apple Store every year or so?

Edit: I found a few posts about air filters on iMac, it seems like it restricts airflow more than the dust ever will.
 
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AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
Here I have idling temps from Macs Fan Control and Windows 10


BTW: I would like to recommend Macs Fan Control to adjust when fan on iMac 5K will start to blow.
I noticed, that on default SMC settings fan won't start to accelerate before reaching 90c. So using this app, allow me to set 55c for starting to speed up a bit before reaching 75c to blow full speed already.
Lets make this sucker work... ;)
 

TheSufle

macrumors member
Feb 13, 2019
52
26
Hi! Guys! I took this problem and glued two fans together, the problem arose in that when you turn on the fans, they run at maximum speed, is there a solution to this problem?


IMG_0119.JPG

IMG_0120.JPG

IMG_0121.JPG
 
Last edited:

AfroUSA

macrumors newbie
Original poster
Jan 9, 2017
16
36
UK
Hi, try to disconnect speed sensor from the second fan, this should solve your problem.

BTW! This looks awesome!!
 
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