4k iMac 2019 21" hardware upgrades

[woefi]

Hi, all!

This summer I finally bought the last upgradable (and also the cheapest) 4K iMac, which I had on my list for almost two years.
Purchase trigger: The price on Amazon dropped from € 1200 to € 940 for the 6core i5, 8GB, 256GB and Radeon 560X model.
It can still run Mojave and 32bit software (In my business I'm still depending a little bit on my dinosaur "Adobe Creative Suite 5" from 2010, never going to rent adobe crApps)

After 3 months of beta-testing Monterey, benchmarking, looking for pixel failures or other problems that may require the 1-year-warranty I finally bit the bullet and ordered the parts of my dream config:
64 GB (32x2) of 2666MHz RAM,
Sintech NVMe adapter,
Crucial P5 1TB NVMe
SATA-cable 923-0641
Crucial MX500 2TB SSD
(...but no CPU*)

The upgrade process went well, as it was absolutely the same as with my older 21" iMac (Late 2013) using iFixit's instructions.
After adding RAM, my Geekbench 5 Multi Score went up from 4850 to nearly 5500!! (really didn't expect THAT...)

* I still am looking for a reasonable option to upgrade my CPU, as I know it isn't soldered (socket 1151):
-> Has anybody tried to replace the i5-8500 with a i9-9900(non-k)? TDP would be the same 65W, and it is also Coffee Lake – the bigger 27" model also uses the 9th gen so I suppose the lazy programmers included the same cpu support in the firmware.

 

[Nguyen Duc Hieu]

It was done on 27" model.
I don't find any excuse why it can't be done on 21.5" model.

 

[uller6]

Glad the upgrade went well @woefi ! I have the same iMac (but with core i3 cpu). The core i3 is surprisingly capable, considering it has no SMT or turbo boost. I’m planning on upgrading the CPU to an i7 in a few years once prices on used CPUs come down. I’m looking forward to seeing your future updates on this!

Mine only had a HDD originally, so no pcie motherboard slot to add a blade ssd. But I replaced the HDD with a crucial MX500 already, which made a huge difference, and the machine already had 32G ram factory installed.

I use mine to run virtualized Windows XP for some mission critical work software, which after a year of trying I still haven’t been able to replace using my M1. I prefer to use an iMac with virtualized windows than a janky windows box, and I got a really really good deal on this iMac after the M1 macs were released last year. I hope it lasts until at least 2025.

 

[woefi]

why it can't be done on 21.5" model

Well I hesitate to order the CPU because, although the TDP is "on paper" the same, I suspect it would push the thermal situation so that the fan would come on much earlier.
And because I'm not sure the firmware is expecting this chip, let alone actually being optimised for it...

Also, I would have to order it from amazon marketplace via UK which will now (br*xit) cost additional custom fees (~70€) so I would not be able to easily return it after an unsuccessful test. Selling it used would be difficult, because it is a very unusual CPU.

Does anyone know what would happen if you put in a CPU with a higher TDP - say a i7-9700"K"?
Would it only throttle down once it reaches the max. power consumption? Would it even boot?
I have an i5-9600K (TDP95W) installed in a PC right next to it...

 

[opeter]

At least in theory you could swap the CPU for any of the 9xxx models.

Here are some gentlemans, who made different CPU upgrades (mostly the i9 models):

9900T

9900

9900K

 

[Nguyen Duc Hieu]

Does anyone know what would happen if you put in a CPU with a higher TDP - say a i7-9700"K"?
Would it only throttle down once it reaches the max. power consumption? Would it even boot?
I have an i5-9600K (TDP95W) installed in a PC right next to it...

Thermal throttle is the norm for AIO system.
Another problem is weak PSU.
It happens even on a decent PC case. At full stress, the CPU may consume somewhere between 125W to 150W.
If the mainboard or the PSU fail to supply enough current to the CPU, it will freeze, hang or shutdown the computer.
One can power it back again without any problem, but unsaved work maybe lost.

 

[woefi]

Here are some gentlemans...

Thanks for the links!
I remember watching Luke Miani's video some months ago. This would be the use-case that mostly matches my situation.

What's different:
my GPU is a 560x, which has the same metal benchmark as the M1 iMac. (21500)
I have the NVMe-slot AND bought the SATA-cable, so I can use 2800MB/s for the NVMe and have plenty additional storage on the SSD
64GB > 32GB (Luke) > 16GB (M1)

I mostly use Capture One (should use metal by the next version), Affinity Apps (metal), DaVinci Resolve (metal), Blender (no metal for now), and my old Adobe CS5 /32bit and Lightroom 6 /64bit (need Mojave as a boot option)

 

[opeter]

Your welcome. I personally would look after/search for the T series 35 W TDP CPUs or the standard 65 W TDP CPUs (the F series are without the integrated GPU).

So that means the following 65 W TDP CPUs:
i5-9400 (or F)
i5-9500 (or F)
i5-9600 (or F)
i7-9700 (or F)
i9-9900 (F version doesn't exist with 65 W TDP)

and the 35 W TDP version of these:
from i5-9400T to i9-9900T

Here is a complete list of these CPUs:

Intel 9th Gen Core Processors: All the Desktop and Mobile 45W CPUs Announced

www.anandtech.com

 

[woefi]

In iFixits comments I found this guy's video. He installed a "K" although he did not say how it performed, or how the thermals were.
But as I'm not signed up in YT I cannot comment to ask him directly...

 

[woefi]

As the 9900 is not really available for a reasonable price I was wondering if anyone tried to put in a i7-9700?

Considering the i9 would be constantly throttled down anyway, maybe the newer i7 (8c instead of 6c of the old i7-8700) would be more sustainable for heavy long term tasks.

Geekbench numbers would suggest a change of <50% (from 4600 to 6500/7000)
But of course this would be not as "extreme" anymore...
Along with the 560x I would nearly match the M1 iMac but with better internal storage and memory options (2+1TB, 64GB).

 

[opeter]

It should work.