Processor upgrading in iMacs.

Quad 2.5 G5 =)

macrumors 6502
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Mar 29, 2009
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Since the new iMacs have socketable processors, is it possible for someone to pop a, for example, a Q9650 LGA775 processor into the C2D iMacs, if one wanted to?
 

MacHamster68

macrumors 68040
Sep 17, 2009
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Since the new iMacs have socketable processors, is it possible for someone to pop a, for example, a Q9650 LGA775 processor into the C2D iMacs, if one wanted to?
everything fits in the socket as long as its a LGA 775 processor and intel ,so you could even fit a celeron d inside if you get forced to, the only thing that might happen is that in the "about this mac" info the processor is shown as unknown processor .2.4 ghz depending on the processor used the ghz may vary
 

Hellhammer

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Dec 10, 2008
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AFAIK, you can stick in any LGA 775 CPU if you want. That means all Core 2 Duos and Quads etc. As MacHamster68 said, it might shown as "unknown", but it's very unlikely that there would be problems with drivers etc, but I haven't that this has been done before so you would be a tester. In addition, make sure to check the TDP of the CPU if you're going to change it so your iMac won't overheat (I would prefer to xxxxS series. They are more expensive but runs cooler)
 

MacHamster68

macrumors 68040
Sep 17, 2009
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i think thats the only thing realy to take in consideration when planning to upgrade the cpu , as others already have "complained "how hot their iMac already gets

but casemodding would be a answer to that , more efficient fans and maybe a second or wider opening at the exit
as a faster processor is producing more heat which needs to get away from the inside
 

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macrumors 6502a
Dec 28, 2009
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I was going to attempt this in my 21.5" iMac, I planned to test a quad core processor, however, I know for instance that the Q9550 will not work as the processor has to high a TDP. The iMac will boot to the grey screen and nothing more. My theory is that a Q9550s with it's lower TDP would work.
 

Hellhammer

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Dec 10, 2008
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I was going to attempt this in my 21.5" iMac, I planned to test a quad core processor, however, I know for instance that the Q9550 will not work as the processor has to high a TDP. The iMac will boot to the grey screen and nothing more. My theory is that a Q9550s with it's lower TDP would work.
The TDP has nothing to do with booting. The firmware doesn't just support it so it can't get past the white loading screen.
 

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macrumors 6502a
Dec 28, 2009
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The TDP has nothing to do with booting. The firmware doesn't just support it so it can't get past the white loading screen.
Q9550 is 95w and 9550s is 65w. That could well be why the Q9550 will not "boot" beyond the grey screen. I think the EFI is fine.
 

Hellhammer

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Q9550 is 95w and 9550s is 65w. That could well be why the Q9550 will not "boot" beyond the grey screen. I think the EFI is fine.
The TDP is just the amount of electricity it uses. Only issue that the TDP might cause is that the power supply isn't powerful enough to power it but I doubt it's causing this problem. There is something different in C2Q than in C2D so it won't work.
 

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macrumors 6502a
Dec 28, 2009
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How do you know the EFI is not allowing the iMac to boot because of a voltage issue?

It is reasonable to assume the Q9550S with it's lower power requirement will work.

"There is something different in C2Q than in C2D so it won't work."

I agree, that difference is that the power requirements differ. A Q9550S is widely speculated to work. Until somebody tries it then I think we have to agree to disagree.
 

MacHamster68

macrumors 68040
Sep 17, 2009
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i dont think the power is the problem the psu has enough power to allow the quad , its the firmware thats stopping
the whole process
the mac is still a simple computer and the firmware is in theory nothing else as the bios in a pc , and in the bios you can restrict a lot of things
maybe it is the heat , so apple did take the ability to upgrade in consideration and to make sure it does not overheat they restricted the choice of processors

that would give them the chance to offer the faster quad later as a option by simply doing a firmware update

the other thing to remember is they want to sell the macpro's too , if they offer every upgradepossibility for the iMac why would anybody buy a macpro then..at least in the 27" would be enough room for a dual processor board

so i guess apple is well aware on what they are offering as upgrade possibilities and they can control it via the firmware (warranty or not)
 

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macrumors 6502a
Dec 28, 2009
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i dont think the power is the problem the psu has enough power to allow the quad , its the firmware thats stopping
the whole process
the mac is still a simple computer and the firmware is in theory nothing else as the bios in a pc , and in the bios you can restrict a lot of things
maybe it is the heat , so apple did take the ability to upgrade in consideration and to make sure it does not overheat they restricted the choice of processors

that would give them the chance to offer the faster quad later as a option by simply doing a firmware update
I agree that the PSU is capable, the EFI on the other hand may enumerate a rule that states "Processor = 65w". Apple would not have purposefully limited the processor inside the iMac as a consumer would void any warranty in removing the heat sink anyway so why would they bother?

The 65w restriction on the processor seems the most likely so again a Q9550S should work. I also feel the need to add that Apple will not be offering a Core 2 quad option in future. (that's your theory of a firmware update thrown out) The reason being that they already have quad core iMacs.
 

Hellhammer

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Dec 10, 2008
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I agree that the PSU is capable, the EFI on the other hand may enumerate a rule that states "Processor = 65w". Apple would not have purposefully limited the processor inside the iMac as a consumer would void any warranty in removing the heat sink anyway so why would they bother?

The 65w restriction on the processor seems the most likely so again a Q9550S should work. I also feel the need to add that Apple will not be offering a Core 2 quad option in future. (that's your theory of a firmware update thrown out) The reason being that they already have quad core iMacs.
Explain me why the i7 iMac has 95W CPU inside and it runs the same firmware
 

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macrumors 6502a
Dec 28, 2009
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Explain me why the i7 iMac has 95W CPU inside and it runs the same firmware
They run the same EFI? I was always under the impression the i5/i7 used a different logic board to that of the Core 2 duo models. The two would need different EFI sets as they are different hardware.

Got any proof they are the same?
 

Hellhammer

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They run the same EFI? I was always under the impression the i5/i7 used a different logic board to that of the Core 2 duo models. The two would need different EFI sets as they are different hardware.

Got any proof they are the same?
Hmm, you're right. They do use different logic boards as i5/i7 requires LGA 1156 while C2D requires LGA 775 and likely a different EFI as well. But it still doesn't make sense that there would be TDP limit (at least I've never heard that it's even possible). More likely Apple has just "somehow" disabled them in firmware or in OS X so that they cannot be used so people can't make their own quad core iMacs but are forced to buy Apple's. You could be right but the TDP limit sounds weird and you have nothing to prove it
 

Quad 2.5 G5 =)

macrumors 6502
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Mar 29, 2009
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They run the same EFI? I was always under the impression the i5/i7 used a different logic board to that of the Core 2 duo models. The two would need different EFI sets as they are different hardware.

Got any proof they are the same?
They obviously are different logic boards, as the C2D/C2Q series work with the LGA775 socket, and the i-series uses the LGA1156. This works out to :apple:'s advantage, as when they refresh the iMacs with the dual core i3/i5 series, so they can just drop the C2D boards, and replace them with said models. The only thing they have to re-do is the 21.5 inch models, as they don't come with any i5/i7 models.
 

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macrumors 6502a
Dec 28, 2009
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Hmm, you're right. They do use different logic boards as i5/i7 requires LGA 1156 while C2D requires LGA 775 and likely a different EFI as well. But it still doesn't make sense that there would be TDP limit (at least I've never heard that it's even possible). More likely Apple has just "somehow" disabled them in firmware or in OS X so that they cannot be used so people can't make their own quad core iMacs but are forced to buy Apple's. You could be right but the TDP limit sounds weird and you have nothing to prove it
I agree with all of that and would like to say thank you for giving me some interesting reading on these forums for a change.
 

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macrumors 6502a
Dec 28, 2009
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They obviously are different logic boards, as the C2D/C2Q series work with the LGA775 socket, and the i-series uses the LGA1156. This works out to :apple:'s advantage, as when they refresh the iMacs with the dual core i3/i5 series, so they can just drop the C2D boards, and replace them with said models. The only thing they have to re-do is the 21.5 inch models, as they don't come with any i5/i7 models.
TBH I thought it was that obvious it didn't need explanation. Different architecture - different sockets.
 

Quad 2.5 G5 =)

macrumors 6502
Original poster
Mar 29, 2009
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I agree with all of that and would like to say thank you for giving me some interesting reading on these forums for a change.
Also, I recall when, before the 9400M Minis, one could upgrade the C2D processor in it, to something with a bit more power, and with the Mac Pros, they can get upgraded, so it must be something else.