iM 4,1-14,4 Running hot: Core i5 - late 2009 - 27"

[exploradorgt]

I often have other computers running too so it gets hotter than I feel comfortable, especially during summer.

About a year ago found a YT video from someone from Germany, I think..., the guy modified the computer case (tower) and added a duct elegantly integrated to his desk and room walls going directly out the window. The computer fan would take room temperature air, move it inside the computer to keep it cool, and then the heated air went out the window to dramatically avoid the temperature increase.

I did the same to an old laser cutter I had around, placing it inside a closed case with a duct directly to the window, I efficiently avoided heat and the fumes.

during winter I rarely need to turn heating on in this room. And I live in the Nordics. 😂

That's really cool.

If the grille under the stand of an iMac is meant to vent heat, then maybe some means of positioning a smaller fan over it to make it an active vent might help. Again, a 12v fan run at 5v would be quiet, but might have a reasonable effect?

Do you mean this one? the vent right below the stand-thing?

It is worth exploring, but my mac doesn't have that vent on the back, so I can't say. I honestly don't know how this vent works on such imacs (taking air in? or out?). In my case (like picture above), it would be ideal to place a fan inside taking the air out.

I've done some experiments myself with fans on closed boxes and rooms, a fan taking the air out will always work better placed inside.

If you mean these (intake vents, right below the screen)

I already tried placing a fan there pushing lots of air in. It works, but in no way comparable to the efficiency of sucking the air from the top instead of pushing it from below.

Again, a 12v fan run at 5v would be quiet, but might have a reasonable effect?

It really depends on several factors:

1. Not all 5v fans are equally powerful or efficient in power consumption, same with 12v fans
2. Some 12v fans will barely move using 5v, some will do a great job
3. At the end of the day what we need is a decent capacity to move specific amounts of air per minute

As far as my personal experience goes (locally), these small fans don't come with an specific rating at the electronic store, they just have 5v, 12v and 120vAC fans, that's it, and the rating for amps, but nothing else. In the past I needed to cool some electronics without making much noise, and the only way to do this was testing one fan after another. I found some (removed from laptops being VERY efficient in terms of moving air and energy consumption).

 

[DCBassman]

What? No, I might misunderstand you but.... heat goes up and fan blow direction is up. So, intake is under the case and exhaust is the thin wide slot in the upper backside of the case. Here I am using my english skills and thinking vent means letting the heat out of the case (?).

Then maybe that grille is an intake? Could still push extra air in, I suppose...

 

[ToniCH]

Then maybe that grille is an intake? Could still push extra air in, I suppose...

Ah, I've never noticed that grille underneath the stand before. I really had to take a look. I have a golf ball sized round vent under the stand and above the power plug. No idea if its intake or exhaust. Would need to see what the insides look like.

Ah, but I do have a pic of it. Here is my deceased Late 2009 iMac 27":

Next I guess I need to find a pic with the motherboard in place. Its very low to be exhaust though.

Note that the exhaust in top part of the case is actually quite good. It looks very limited from outside but there are lots of holes up there.

 

[ToniCH]

Next I guess I need to find a pic with the motherboard in place. Its very low to be exhaust though.

Ok, here is my 2011 iMac (installing a SSD under the SuperDrive). Not the same but the vent is the same on both. To me it looks like the round grille is the hard disk fan intake (?).

 

[exploradorgt]

Ah, I've never noticed that grille underneath the stand before. I really had to take a look. I have a golf ball sized round vent under the stand and above the power plug. No idea if its intake or exhaust. Would need to see what the insides look like.

Ah, but I do have a pic of it. Here is my deceased Late 2009 iMac 27":
View attachment 2255452

Next I guess I need to find a pic with the motherboard in place. Its very low to be exhaust though.

Note that the exhaust in top part of the case is actually quite good. It looks very limited from outside but there are lots of holes up there.

Mac 27" - 2009, it's an air intake.

My bad on my previous comment, I was looking for the rectangular shape with horizontal spaces. Mine it's round, confirmed, it's an air intake.

 

[Nguyen Duc Hieu]

That's the reason why I still set the HDD fan on as high as possible (normally 3500rpm) to get as much air inside my iMac as possible, even after an SSD upgrade.

 

[exploradorgt]

The more I search the web, the more I find reports, testimonials and complaints about the aluminum iMacs generating too much heat on the top, specially the top left (variety of models).

I'm curious on design-efficiency, not just the cooling-venting, I mean, regarding the differences in power consumption (and heat generation) between using the iMac with the screen off (via remote desktop) and using the LCD screen. It gets interesting when compared to similar computers (non Mac), or just monitor screens and tvs, both 27" and 32".

I can understand such huge computer came prepared to provide enough power to lots of peripherals connected via USB or Firewire, etc, but in general... but normally switching power supplies would adapt to the power consumption needs, up and down. And... whenever too much heat is being generated, it means too much electricity is being burned, not... used...

 

[ToniCH]

The more I search the web, the more I find reports, testimonials and complaints about the aluminum iMacs generating too much heat on the top, specially the top left (variety of models).

I would like to introduce a thought: is the top really hot or does it just feel hot? I mean I thought it is really hot by just touching it. But, then I used an IR temp gun to measure what it really is and it was only 41°C. That was 7°C less at that time than CPU temp. And the CPU temp was nowhere close to the max temp for an i7 CPU.

So, I don't worry about it anymore.

 

[Nguyen Duc Hieu]

I would like to introduce a thought: is the top really hot or does it just feel hot? I mean I thought it is really hot by just touching it. But, then I used an IR temp gun to measure what it really is and it was only 41°C. That was 7°C less at that time than CPU temp. And the CPU temp was nowhere close to the max temp for an i7 CPU.

So, I don't worry about it anymore.

Many of them have survived those heat for twelve or more years. Why do we have to worry about now?

 

[MultiFinder17]

If you're curious, here are the temps on my 2010 27" iMac after playing back some YouTube for about 30 minutes. The top right corner is always plenty toasty ^_^

 

[exploradorgt]

I would like to introduce a thought: is the top really hot or does it just feel hot? I mean I thought it is really hot by just touching it. But, then I used an IR temp gun to measure what it really is and it was only 41°C. That was 7°C less at that time than CPU temp. And the CPU temp was nowhere close to the max temp for an i7 CPU.

So, I don't worry about it anymore.

Just tried with a digital (physical) health-thermometer, but mine stops at 44 Celcius because that's it's limit, I don't have another one to try right now. As for the IR temp gun you mention, as far as I know, that method is not accurate regarding stainless steel and aluminium (and water).

Right now I've been using the iMac for a while watching/listening vids on YT a high res while copying files over my network. The CPU temps don't go beyond 50C; GPU don't go beyond 48C; it's the LCD proximity the one going above those values, currently at 62C and steady.

Many of them have survived those heat for twelve or more years. Why do we have to worry about now?

So true.

While using Windows too, I've been using Macs daily since the Classic and Performa era until the G3, then rarely a G5. But then moved to Windows permanently, so I've been disconnected from Mac hardware except from MacBooks and Macboks Pro, my wife owns a MBP currently. Turns out now I'm discovering via personal experience and lots of reading that the heat production has been way different from my times. I feel more confident with this iMac now.

Worry? you are right. Yet, I'm still a bit concerned about the power consumption and efficiency regarding component lifetime, perhaps my biggest influence it's the pack of computers I've been using over the recent years... very low heat production and quite efficient.

If you're curious, here are the temps on my 2010 27" iMac after playing back some YouTube for about 30 minutes. The top right corner is always plenty toasty ^_^

Nice, thanks, here are mine:

I'm quite surprised about my findings over the web, people who have tested these things explaining it's the LCD the one producing the most heat. I tried using the mac for a while and then opening it to remove the LCD, oh boy! it's true.

 

[exploradorgt]

Made a few changes and I'm seeing improvements. In my case yes, the PSU gets hot (naturally), but it's the LCD backlight LED driver that's actually getting hotter. Used the computer for a while and then removed the parts, the PSU was hot, but the coils on the LCD led driver were really hot. There is no enough space to add any heatsink there, and there is no way to make sure it stays fixed, so no. The plastic walls don't allow any airflow in, and there is no airflow going out.

For some reason there was a 3mm gap between the vertical fan and the CPU heatsink. I wondered if by design they wanted most of the air to flow up via the CPU heatsink while allowing some extra air to flow behind the LCD. I bought this second hand so there was no way to know except looking at pictures on the web. Seems to me that originally there is no gap there. Also, there is a plastic wall making it impossible for air to flow on the back of the LCD driver.

Below is the original distribution.

Naturally, I wanted to improve this.

1. So I just removed a piece of the plastic wall and made sure air flows up behind the PCB of the LCD driver allowing some cooling of the parts, specially the coils.
2. Then covered that semi triangle with tape to avoid the air from escaping.
3. And below, added some tape to make sure the air flowed directly from the vertical fan into the heatsink.

The whole thing looks like the pic below. I do notice airflow (little but it's something) going over the LCD LED driver components and coming out at the top, so yes there is some cooling now where there was none. The CPU heatsink is now receiving more air, probably as it was original intended, I guess someone made some not-so-good tech service to the machine before me, it's now fixed.

Results? the temperature of the components stays now 1, 2, 3 degrees or more lower than before. The top left of the iMac case takes a bit longer to heat up, and it's not heating the same way as before. Yes I'm using Macs fan control. But overall, the heat perceived externally is lower, specially to the touch.

 

[exploradorgt]

I also made an extra modification

The original HDD is too slow by modern standards, and I don't need the optical drive, so the first thing I did was adding an SSD in a caddy there. The machine literally flies, but... the USB ports are too slow, network speed is limited, and I'm talking about moving backups or large files 20-50-70 Gigabytes, that's too slow!!!, plus, after replacing the GPU I have no boot menu.

So I made a small horizontal hole at the back next to the vertical stand and circular vent (mine is circular, not square). Now the ODD data+power cable goes out that hole. The hdd caddy (DVD box) is elegantly glued to the stand, it looks really cool because it's aluminum. And the caddy (that I made myself out of a dead DVD and some cables+connectors) allows me to insert and remove my SDD as if it was a floppy disk.

Now I can copy files easily AND FASTER to my main computer and mount the SSD via USB3 hdd-sata-adapter, it's obviously way faster, and this way I can also make special backups (like fully clone the drive, etc quite fast). There is some dutch tape there to close the gap, doesn't look perfect but it's something. I thought about using some epoxy mixed with thermal past to create some shiny compound, but no... because at some point I might need to remove that cable, so the whole space will be needed. Naturally, the heat sensor of the original DVD is glued to the inside of the case to avoid issues.

 

[exploradorgt]

Many of them have survived those heat for twelve or more years. Why do we have to worry about now?

I understand you own one of these 27" - 2009 models, but you have one (or at least one) with a video controller board to reuse the screen. I also remember you mentioned this method doesn't allow full brightness (it's about 80% I think), and I've seen the same testimonial around the web.

So yes I understand, less brightness. My question is: does it heat up as in the past? when it was a full computer?

I might try to create my own LED driver to avoid the heat of the one coming with the computer, originally. I fully understand the LCD board will generate heat, both the screen and the leds. The color leds are unavoidable, but the backlight leds can be kept cooler. At least, I might fully remove the driver board.

 

[exploradorgt]

Running cool? cooler? chilling!

Today decided to try Linux Ubuntu, I don't want to sound like a broken record but... it runs really fast and fine, I have full brightness control (real control) and the whole system runs really cool (in temperature terms), in fact I'm not even using any fan control app. The CPU + LCD + LED driver and the GPU run at normal temperatures. The computer doesn't get hot at all, in fact it only gets slightly warm while watching a high res movie while also watching a full movie on Youtube. Not needing any fan control is really cool, as there is no background noise.

However, the official Nvidia GPU drivers don't fully work. There are 2 official versions, if I use any of those... I loose real brightness control (and there are tons of reports about Nvidia Quadro and GT whatever video cards with the same issue). BUT, if I use the generic XORG drivers (the ones Ubuntu uses by default), then everything works perfectly.

Keep in mind that my GPU is an Nvidia Quadro 1000m, I don't have any boot menu (mac). The card works perfectly under Windows 10, except the lack of real brightness control, and so the LCD and led driver + PSU get hot.

I'll keep testing, perhaps I'll try to install Windows 7 or 8.1 out of the box with default drivers to see what happens.

 

[Nguyen Duc Hieu]

I understand you own one of these 27" - 2009 models, but you have one (or at least one) with a video controller board to reuse the screen. I also remember you mentioned this method doesn't allow full brightness (it's about 80% I think), and I've seen the same testimonial around the web.

So yes I understand, less brightness. My question is: does it heat up as in the past? when it was a full computer?

I might try to create my own LED driver to avoid the heat of the one coming with the computer, originally. I fully understand the LCD board will generate heat, both the screen and the leds. The color leds are unavoidable, but the backlight leds can be kept cooler. At least, I might fully remove the driver board.

I have 2 iMac 2009, both are running Mac OS.
The one I converted to stand-alone display is the iMac 2011, it use a slightly different signal cable from iMac 2009.
With only the LCD panel and a 12V 8A adapter to generate heat, it's quite cool.

 

[exploradorgt]

I have 2 iMac 2009, both are running Mac OS.
The one I converted to stand-alone display is the iMac 2011, it use a slightly different signal cable from iMac 2009.
With only the LCD panel and a 12V 8A adapter to generate heat, it's quite cool.

Thanks

 

[exploradorgt]

I just solved this issue, I now have full brightness control on this iMac via hardware modifications. The computer runs really cool now, I'm not even using MacFans control.

In order to give a bit back I posted some details here: https://forums.macrumors.com/thread...non-officially-supported-gpu-upgrade.2405748/