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can i put i7-9700k or i9-9900k in iMac 21.5 2019?
- Thread starter Amethyst
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I can only speak from historical and general knowledge since I don't know the specifics of the 2019 iMac.
Generally as a rule of thumb you don't want to install a CPU with a TDP higher than the OEM intended/uses with a laptop or AIO. Space is limited in those devices so heat sinks, fans, power supplies and voltage regulators on the logic board are typically sized for the application.
This is especially important with the 9700K and 9900K. I'll try to explain it really briefly but Intel TDP (thermal design power) is the cooling requirements to maintain base frequency. TDP is also the first power limit of the CPU which is know as Power Limit 1 (PL1). Power Limit 2 (PL2) is the turbo clock power limit. PL2 is generally a multiplier based on TDP (traditionally its TDP x 1.25) and it uses an algorithm of temps, cores, power usage, and time (tau) to control its duration.
However with the unlocked 9900K Intels sets PL2 to 210 watts. This is the power required for all cores turbo. Real world usage the 9900K is around 160-170 watts under load (taking into account metrics like temperature are ok).
The 21.5" has a smaller CPU cooler (heat sink and fan) making it unlikely you'd even be able to maintain base frequency.
However I think that's the least of your worries because in the past the 21.5" iMac used a 180 watt PSU. So assuming the computer would boot at all a turbo boost power spike of 160-170 watts would likely cause the PSU to hit OCP (over current protection) since its also powering everything else, including the monitor.
Again though, I've never seen anyone try it so I'm not aware of the real world results.
Generally as a rule of thumb you don't want to install a CPU with a TDP higher than the OEM intended/uses with a laptop or AIO. Space is limited in those devices so heat sinks, fans, power supplies and voltage regulators on the logic board are typically sized for the application.
This is especially important with the 9700K and 9900K. I'll try to explain it really briefly but Intel TDP (thermal design power) is the cooling requirements to maintain base frequency. TDP is also the first power limit of the CPU which is know as Power Limit 1 (PL1). Power Limit 2 (PL2) is the turbo clock power limit. PL2 is generally a multiplier based on TDP (traditionally its TDP x 1.25) and it uses an algorithm of temps, cores, power usage, and time (tau) to control its duration.
However with the unlocked 9900K Intels sets PL2 to 210 watts. This is the power required for all cores turbo. Real world usage the 9900K is around 160-170 watts under load (taking into account metrics like temperature are ok).
The 21.5" has a smaller CPU cooler (heat sink and fan) making it unlikely you'd even be able to maintain base frequency.
However I think that's the least of your worries because in the past the 21.5" iMac used a 180 watt PSU. So assuming the computer would boot at all a turbo boost power spike of 160-170 watts would likely cause the PSU to hit OCP (over current protection) since its also powering everything else, including the monitor.
Again though, I've never seen anyone try it so I'm not aware of the real world results.
The highest option is an i7 8700. This is a hex core part with hyper threading.
It won’t accept the k chips or the 8 core chips
It won’t accept the k chips or the 8 core chips
I think it's possible to put i7 9700k or i9 9900k to imac 21.5 inch 2019 (base version core i5 8600) because both of them has TDP 95W. In the past, someone has put i7 7700k (TDP 91W) to imac 21.5 inch 2017. Check out this video:
Now, you can put i9 9900/9900K/9900T/9900KF to imac 21.5 inch 2019 but performance of 9900/9900K/9900KF may not be high because of temperature
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I found one post from UK that gave promise. For the fun of it I replaced the 8100 i3 with a 9900 i9. The TDP’s are the same (65w). Same microcode, socket and coffee lake family. The 9900 has integrated graphics as well.
Works great!
Cinebench went from 2900 to 9600.
Put through the ringers with Tomb Raider, Diablo III, at max everything. Temp goes to 95c but fan cools easily and cycles normally- does not stay on suggesting inadequate cooling.
Used > 5 hours straight and not any issue. Sure, wasn’t designed with that intent but as a hobbyist I wanted to try.
Used Arctic MX-4 generously on the CPU, GPU. Yes, violates all warranties, but I wanted to try.
Some report things not working but maybe something mis-aligned? The CPU heat sink is tough to replace, I think on purpose.
Nice project. As very few reports that I found anywhere, but certainly a 9900 seems to be similar enough and even the stock 8700 option reaches 95 degrees as well, I read.
Ive not had the iMac turn off due to heat. The design of i9 will throttle if heat high. The fan doesn’t remain on during continuous gaming suggesting enough cooling is occurring.
i had also increased ram to 32 GB and placed a Samsung evo 1tb SSD.
cheers!
Works great!
Cinebench went from 2900 to 9600.
Put through the ringers with Tomb Raider, Diablo III, at max everything. Temp goes to 95c but fan cools easily and cycles normally- does not stay on suggesting inadequate cooling.
Used > 5 hours straight and not any issue. Sure, wasn’t designed with that intent but as a hobbyist I wanted to try.
Used Arctic MX-4 generously on the CPU, GPU. Yes, violates all warranties, but I wanted to try.
Some report things not working but maybe something mis-aligned? The CPU heat sink is tough to replace, I think on purpose.
Nice project. As very few reports that I found anywhere, but certainly a 9900 seems to be similar enough and even the stock 8700 option reaches 95 degrees as well, I read.
Ive not had the iMac turn off due to heat. The design of i9 will throttle if heat high. The fan doesn’t remain on during continuous gaming suggesting enough cooling is occurring.
i had also increased ram to 32 GB and placed a Samsung evo 1tb SSD.
cheers!
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Reviving this old thread...did you do the CPU upgrade? I have a 2019 iMac 21.5" with a puny i3-8100 CPU. I'm considering the upgrade to an i7-8700K which I can buy off eBay for around $100-$125 these days.
Already upgraded the sloooooow 5400rpm 1TB with an SSD and went from 8GB to 32GB, and it's finally running pretty nice, but definitely want to upgrade the CPU.
Thanks! I know originally you thought of putting the i7-8700K which is why I was asking the question. Definitely moving forward with the upgrade!!
Hello Jamitche!
I’ve a similar upgrade in my mind but I have some doubts about the iMac 21.5 2019 that you have.
Can you confirm you have the base model which came with base i3-8100 cpu and without pci-e slot on the logic board? You’ve upgraded with no issues from the i3-8100 to the i9-9900?
I’ve tried to upgrade with i7-9700 and i7-8700, same socket, same tdp, but no luck!
It the first case: the i7-9700 booted the system but won’t pass the Apple logo screen. In the second case: the i7 8700 didn't boot at all!
I don’t know what to think.
Did someone performed the upgrade from the i3-8100 on an iMac base model without pci-e?
Thank you all!
Not sure what to tell you- I started with the lowest end iMac from Costco. I also changed to an SSD drive and 32gb ram.
These CPU’s- are you buying them new off Amazon or Newegg? eBay has lemons at times. I didn’t try an i7- just the i9 9900 (without k) and I guess make sure unlocked processor. Used the said iMac yesterday and works fine. Not sure what to say.
Yea it’s true.. sometimes on eBay I’ve receive the entire lemon tree! 😂
The i7s that I bought were new and never used, tested and in good condition… but who knows how they test them ?
I can bet that they test them with windows pc components, for sure not with iMac logic boards!
At the end, do you have the same my logic board iMac without pci-e slot?
Since you had to change the HDD with a SSD I think that you don’t have the pci-e slot.
You said something about the microcode of your i9 being the same of the i3, does it mean that there’re some CPUs not compatible with the logic board even they are the same family ?
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That’s an excellent work!
Thank you for taking your time posting these pictures.
On my logic board there’s a space near the I/O panel with many pins where there should be the pci e slot.
I’m attaching the picture of my logic board:
