Ideas for cooler PSU in fat iMacs?

[Eugen Mezei]

Anybody tried replace the power supply in the late2009-mid2011 iMacs?
As well known these get hot.
The tapered iMacs run much cooler, so obviously cooler PSUs are possible to build.
I would be happy even with an exernal soulution, feeding the iMac trough a cable.

What makes me angry is that running the fans to keep the PSU somewhat cool (still hot) sucks dust into the LCD. After half day of running the fans adapted to the temperature (not at max speed, although I also let them run for half an hour at max) the dust that already was at the edge of the screen wandered around 20 cm further toward the middle of the screen, now I have a big spot.

 

[Bodhitree]

The dust buildup and heat may also eventually cause components like the GPU to fail. Well known issue with these machines.

 

[pshufd]

I have 2009 and 2010 iMac 27s and they both work. The HDD fan sensor in the 2010 is gone but I just use Macs Fan Control to fix that.

The back case of these systems get pretty hot but I find that the actual sensor thermals are okay. The 2010 is better than the 2009 in this regard but I think that's due to better CPUs (I have the Core 2 Duo in the 2009 which is really weak). If the thermals are really bad on your system, then you could try a quiet fan to blow air on the back of the case. I think that these iMacs just have a heat dissipation problem but it appears that this was the design.

The thin iMacs are, as you say, much better in terms of case temperatures but I find that the sensor temperatures are higher in the "blade" design.

 

[visusest]

The foam tape that’s supposed to seal between the LCD and front glass may be worn out and not making good contact anymore. I just threw the calipers on my 2011 27” since it’s sitting with it’s glass off waiting for me to get around to installing a WX4150. The tape is 1mm thick and 5mm wide. Bumping up to a 2mm thick tape may solve your dust ingress issues … https://www.amazon.com/uxcell-Thick-Adhesive-Weather-Strip/dp/B07L6LDQK5

 

[Eugen Mezei]

Visuset, it is not dust between glass and LCD. It is dust in the LCD itself. (There are some tutorials on YT how to clean it, but it is risky as the LCD has to be taken apart and some fine wire can brake.) I think the dust is coming into the LCD not from a gap between it and the front glass but from behind. I have to inspect this further when I will take the iMac apart to instal an SSD. At the moment I am trying to find out if instead a 2,5" SSD it would be possible and make sense to install a blade form SSD with adapter. (My thinking being that it will take less space in the already crowded case of the 2010 and 2011 iMacs.)

 

[BeatCrazy]

Visuset, it is not dust between glass and LCD. It is dust in the LCD itself. (There are some tutorials on YT how to clean it, but it is risky as the LCD has to be taken apart and some fine wire can brake.) I think the dust is coming into the LCD not from a gap between it and the front glass but from behind. I have to inspect this further when I will take the iMac apart to instal an SSD. At the moment I am trying to find out if instead a 2,5" SSD it would be possible and make sense to install a blade form SSD with adapter. (My thinking being that it will take less space in the already crowded case of the 2010 and 2011 iMacs.)

I have a late 2009 iMac and have taken it apart more times than I would like to remember.

Yes, it is delicate to remove the screen and 4(?) associated connections. It's also tricky to get the back of the glass cleaned and put all back together without fingerprints or other debris being seen once re-assembled.

Regarding the power supply... unless you are skilled with some engineering and a multi-meter, I would not attempt to replace the PSU with anything other than an OEM unit. The PSU was not meant to be modified, unlike upgrades to the HDD, ODD, RAM, etc.

 

[Eugen Mezei]

Yes, it is delicate to remove the screen and 4(?) associated connections. It's also tricky to get the back of the glass cleaned and put all back together without fingerprints or other debris being seen once re-assembled.

I am talking about getting the LCD itself apart so that the dust clouds can be cleaned. (This is even tougher as the connectors inside the LCD panel are even more flimsy.) The inside of the glass is clean, that is why I think the dust goes inside the LCD from behind.

 

[visusest]

Visuset, it is not dust between glass and LCD. It is dust in the LCD itself. (There are some tutorials on YT how to clean it, but it is risky as the LCD has to be taken apart and some fine wire can brake.) I think the dust is coming into the LCD not from a gap between it and the front glass but from behind. I have to inspect this further when I will take the iMac apart to instal an SSD. At the moment I am trying to find out if instead a 2,5" SSD it would be possible and make sense to install a blade form SSD with adapter. (My thinking being that it will take less space in the already crowded case of the 2010 and 2011 iMacs.)

Sorry for misunderstanding, I didn’t realize dust getting into the LCD itself was an issue. Replacing the power supply board may lower temperatures and slow the fans. The electrolytic capacitors in the power supply do wear out with age and use. Their electrolyte dries out which causes a drop and capacitance and a rise in impedance both of which could cause higher temps. If you’re handy with a soldering iron (or have a decent local electronics repair shop), replacing the capacitors could help. Regarding a blade type SSD, there isn’t a PCIe slot to use an NVME drive unless you want to give up WiFi and PCIe 2.0 x1 is slower than SATA III so there’s no point. You could run an external Thunderbolt 3 NVME SSD with an adapter for a slight speed advantage.

 

[Eugen Mezei]

All thick iMacs I had have some clouding, so this is an issue unfortunately. Depending of the colour of the background it is more or less noticeable.
I will look into the capacitors issue. Thought if they are not exploded they are fine, but you may have a point here with them getting older.
I want to connect the blade (NVME or M.2) to the third SATA port. Unfortunately I see adapters try to mimic the format of an SSD (I guess for simpler mounting in drive bays) so those will not save space. I am looking for an adapter that is not much more larger than the blade drive.
(Thunderbold I find to be to expensive, for the price of a Thunderbolt drive and the cablage I already can buy a tapered iMac. Enthusiasm also has its limits.)