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Hello, I really need some help with my iMac it is showing - on GPU temperature.
I have even replaced the diode, but still nothing and fans are going crazy because of that. I will be happy if someone can help me.
Here are the specs: Core 2 Duo, 4GB RAM, macOS High Sierra
here is the image
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You’ll need to find someone with Mac repair skills to fix your system. As these systems can be a bit tricky.
First MacsFanControl is not very good as it doesn’t get you enough useful information or offer the better way to manage your systems fan’s if you need to. I prefer this app TG Pro.
But your issue is not the CPU Diode that’s just merely the sensor within the CPU chip frame and not the GPU at all.
Your real issue is likely a simple dust buildup! Over time the fan blades and the heat sink fins get clogged up with dust and other debris making it harder to shed the CPU & GPU’s heat and your reaction is pump up the fans RPM’s which then wears the fans out and at some point one or more fans fail as they where pushed too hard with all of the junk loaded on them!
So the ODD fan gave up and now needs to be replaced! Here’s the guide to get to it iMac Intel 20" EMC 2266 Optical Drive Fan Replacement Here’s one source for the fan 20” iMac Optical Drive Fan, Apple P/N 922-8841
But you really need to pull the logic board so you can get to the head sinks to clean them as well as the other fans iMac Intel 20" EMC 2266 Logic Board Replacement To do it properly you’ll need a small soft paint brush that you can use to scrub the fan blades and cowlings and the head sink fins as well as the rest of the system. Then using a can of can’ed air with short blasts blow away the junk.
Given the age of the system I would also recommend cleaning off the old thermal paste (TIM) and apply a fresh coat. Keep in mind it doesn’t take much for the task! I often got systems in after people tried, they would empty every last bit of what they bought coating everything! So wrong! To help you see how much you really need take a single layer of face tissue cut it down to the size of the chips heat spreader now using some water wet it and roll it into a tight ball thats how big the amount you want of TIM for that chip. Here’s the needed kit to do this job [linked product missing or disabled: IF179-010-2]
Guide
Difficulty:
Moderate
Guide
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Difficult
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thanks i cleaned fans and mainboard and i will replace mainboard
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hey someone, did you get it fixed? having a similar issue with the fans and i believe it's to do with the PSU temp being in the high 60's. got a question myself about it and searching through ifixit for any hiding solutions.
my theory why the fans act this way is: psu is cooled by cpu fan > psu is constantly high temperature > cpu forced to go hard > psu still hot > ODD fan goes hard as a failsafe to increase airflow into the chassis. this fan problem didn't exist when the psu was in the low 40s on another imac that had the t7550, hence my speculation
i don't know why the gpu temperature isn't showing though, sorry. i've forced 64-bit windows 10 LTSC IoT 21h2 on it without a mac partition since i got it without a hdd (protip: burn a windows install DVD that uses legacy boot instead of uefi boot to avoid the nvidia driver crashes, or rEFInd to boot from a legacy bios formatted usb [i used YUMI since Rufus didn't work, and ran diskpart to clean & convert mbr before installing windows). i can only speculate it's because these imacs only officially support el capitan: that high sierra install was a hack (dosdude is your guy for that guide) and an out-dated one of that, since catalina is able to get hacked on (montrery's hack isn't working [yet?])
but yeah replace that thermal paste, just be careful when doing the gpu cause the heatsink is only held on by spring-loaded plastic barbs and not screws, so they might snap. i'm still trying to find an active nvidia heatsink with screwable insulated backplates before i make one myself using a spare heastink off a broken actively cooled ati card and some heatpipes that are long enough lol
oh yeah if you still have the mac os installed, diagnostics is launched by holding D as it boots up. if you have a keyboard with a bios switch (eg. my corsair k65) put it to position 0 (the scroll lock light will flash on and off slowly). you can also try resetting the nvram to see if that helps, some people said it has but it didnt for me. i forget the key combination but i THINK it's cmd+opt+P+R or windows+alt+P+R depending if you have a mac or a normal keyboard
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2 Comments
Can you please post a snapshot of MacsFan Control app which is showing this diode issue Adding images to an existing question
Did you try running diagnostics? Also is the the system having any issues besides this.
by Dan
@danj Hi, I didn't run any tests / diagnostics because I don't know how.
ODD fan is broken too can't change speed,but if i set hdd and cpu to minimum, then the odd speed just start falling.
oh and I am windows user, but one friend pleased me to repair this iMac, so I don't know anything about Mac's
by someone