Swap i7 CPU from Dell into 27" i5 iMac?

Deanster

macrumors regular
Original poster
Jun 6, 2005
236
83
Hi all!

I recently bought a 27" iMac i5, selected over my preferred i7 configuration primarily because I wanted to get it at the local Apple Store and have it be easy to swap in case of screen/build problems.

My 27" iMac i5 is beautiful, and hassle free.

I just ordered a Dell XPS 8100 with the 2.8 Core i7-860 chip in it - that machine doesn't really NEED the i7, but it was a cheap upgrade on Dell's website. I'm reasonably confident that this is the exact same chip used in the 27" i7 iMac.

So, the question - is it POSSIBLE to swap the i5 in my iMac and the i7 CPU's in my Dell?

I know it's difficult (I've previously swapped an SSD into a 20" Aluminum iMac), and I know it would void my warranty, and I may well never actually do it. It's clear that I probably SHOULDN'T do this, but I'm curious as to whether I COULD.

So, the question is, "Is there any reason (sockets, size, heat, speed, other incompatibility) why this swap physically wouldn't work?"

and next, is there anything beyond a physcial swapI need to do to make it work? reset anything on the Dell for it to accept the i5?

All thoughts appreciated!
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
Core i7-860 is used as a BTO option for iMac so I can't see why it wouldn't work.

You may have to update your BIOS in the Dell but I'm not sure of that
 

jav6454

macrumors P6
Nov 14, 2007
16,864
1,480
1 Geostationary Tower Plaza
Core i7-860 is used as a BTO option for iMac so I can't see why it wouldn't work.

You may have to update your BIOS in the Dell but I'm not sure of that
Wrong in many levels... also, BIOS has nothing to do, unless it's a new CPU like i7-980X on already existing LGA 1366 boards.

i7s are no custom built, they are all generic and upgradeable. However, iMac's CPUs are soldered in, so no dice.

Also, OP, if the i7 in the Dell is LGA 1366, it will not work at all, since the iMacs use a different chipset LGA 1156. Only a Lynnfield class CPU will fit in there, that is if the iMac's CPU isn't soldered. Which I believe it is.
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
Don't quote me on this as I'm not 100% sure but isn't the iMac's processor soldered onto the logic board?
Most iMacs before 21.5" and 27" had CPUs soldered onto the logic board because they were laptop CPUs but now that they use desktop CPUs, they are socketed as normal desktop CPUs are
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
i7s are no custom built, they are all generic and upgradeable. However, iMac's CPUs are soldered in, so no dice.
I said i7 iMac were Built To Order (at least were), didn't mean they are custom.

I can't see why it wouldn't work.
I think that means it should work, if not, it was my grammar mistake, but I meant it should work.

also, BIOS has nothing to do, unless it's a new CPU like i7-980X on already existing LGA 1366 boards.
Most OEM PCs like Dell need a BIOS update to upgrade almost anything because the original BIOS is made for the parts that came with (somehow the other HW has been blocked so need newer BIOS). I've faced this multiple times when fixing a computer at work... Doesn't apply to custom PCs though

Also, OP, if the i7 in the Dell is LGA 1366, it will not work at all, since the iMacs use a different chipset LGA 1156. Only a Lynnfield class CPU will fit in there, that is if the iMac's CPU isn't soldered. Which I believe it is.
If it uses LGA 1366, then it's different case... iMacs' CPUs aren't soldered anymore AFAIK, as people have tried upgrading C2D models to Core 2 Quads (won't work due EFI)
 

Deanster

macrumors regular
Original poster
Jun 6, 2005
236
83
Yes - it's waaay past my return date. All in all, it's not all that big a deal - the i5 is plenty fast enough for my general needs. I wouldn't mind the the extra speed, but it's not worth voiding my warranty for.

However, I generally don't buy AppleCare, and might consider doing a swap at some point in the future....

Thanks for pointing out the LGA 1366 issue... that seems like the only significant potential showstopper.

Put on hold for now, but we'll see how this goes in future!
 

DoFoT9

macrumors P6
Jun 11, 2007
17,494
26
Singapore
if you want a speed increase, get a SSD hard drive - or more RAM. you wont really notice the CPU upgrade.
 

cat3600

macrumors newbie
Apr 7, 2010
27
0
I have done it

I bought the i5 and have now replaced it with the i7.

You are looking at a 2 hour job minimum. Once you get the glass cover opened, open 8 screws for the display panel, 4 on left & 4 on right. Be careful (extremely) when you lift the glass as there are 4 connectors & one which is delicate is right at the edge (ribbon style).

Once the panel is out you will have to take of tons of connectors but all easy to take off & put back, there are no chances of getting mixed up as all of the connectors are different sizes (good thing). After that you will have to unscrew the long bolts for the mother board & 2 small ones, 1 near the cpu heat sink bracket corner & 1 near the gpu heat sink corner. When you lift the mother board out make sure the rams are out & pull the casing near the apple logo towards you as the infrared sensor is located through the apple logo in the front. You basically pull the casing just a bit to flex it so that sensor does not get stuck when you are pulling the motherboard out as its located on the motherboard. There is also a clip holding that sensor, so you can also unclip it, which took me sometime to guess. Its a simple clip so no worries. That sensor also has a cable connected to the mother board.

Before you lift the motherboard off, raise it a bit, as beneath it you will find again a couple of cables including the power supply & SATA for the HDD & DVD drive. Once out you will have to unscrew 4 screws that hold the heatsink. there are 2 sticker (warr void, blah blah blah!!!) on one of the screw (one front & one back) once you take them off for sure you cannot lie to apple as the stickers are plain white but turn into a web pattern once you take it off.

Unlock the lever holding the cpu & you are done. It is socket 1156, so check your dell one first. Be careful as the pins for these sockets are on the socket itself & not on the cpu, well even if you buy any motherboard from outside its the same, you have to be careful with these type of sockets!

Apply heatsink paste after you clean up the old stuff, tighten the 4 heatsink screws evenly & diagonally. Reverse the order of sequence making sure you put back all cables, lastly at the end the ribbon cable for the monitor is delicate so be careful! I needed no BIOS update (macs dont have a BIOS) everything works fine.

If you have not built computers dont try it, or if you are handy do it but be extra careful. I have been building computers for 15 years (as a hobby) & this is no different than opening up a laptop etc. or any type of other electronics.

Just be careful thats all, I can do it quite quickly now as I have opened it up twice now & know what to do!

Good luck!
 

Nihilvor

macrumors member
Jan 25, 2010
78
4
Congratulations. That's a really nice upgrade, for those who are competent enough to pull it off. Despite what the previous poster noted, the i7 is a much bigger upgrade than moving up from 4 GB of ram (you won't notice the benefit of 8GB unless you run dozens of professional apps at once). 4GB is more than enough for most users; while everyone's applications will see some real boost from the i7.

Here are the CPU replacement pictures and directions for the 21.5. They might help with the 27", at least until you get to the CPU itself (which is different):
http://www.ifixit.com/Guide/Repair/Installing-iMac-Intel-21-5-Inch-CPU-Replacement/1859/1

Myself... I'm waiting for someone to post whether the 4670 cards (which are confirmed replacable) can be swapped to the 4850 in the 27" and (even more interestingly) the 21.5".


I bought the i5 and have now replaced it with the i7.
...
 

DoFoT9

macrumors P6
Jun 11, 2007
17,494
26
Singapore
I bought the i5 and have now replaced it with the i7.
Congratulations. That's a really nice upgrade, for those who are competent enough to pull it off.
i looked into the upgrade then realised i was stupid for even considering it.

reason?

COST. at the time, the upgrade from apple was $258aus i think (including discount) - to buy the CPU from a store was >$310. and then my time/lost warranty doing the upgrade.

was a simple decision for me.
 

Eidorian

macrumors Penryn
Mar 23, 2005
29,081
287
Indianapolis
Most iMacs before 21.5" and 27" had CPUs soldered onto the logic board because they were laptop CPUs but now that they use desktop CPUs, they are socketed as normal desktop CPUs are
All of the Intel iMacs have used socketed processors. Not that it's a fun job installing a new one in the iMac.

It's four screws and a latch to replace the processor in my tower. The CPU fan/heatink and thermal paste are the most annoying part to be honest.
 

ayeying

macrumors 601
Dec 5, 2007
4,548
11
Yay Area, CA
I bought the i5 and have now replaced it with the i7.

You are looking at a 2 hour job minimum. Once you get the glass cover opened, open 8 screws for the display panel, 4 on left & 4 on right. Be careful (extremely) when you lift the glass as there are 4 connectors & one which is delicate is right at the edge (ribbon style).

Once the panel is out you will have to take of tons of connectors but all easy to take off & put back, there are no chances of getting mixed up as all of the connectors are different sizes (good thing). After that you will have to unscrew the long bolts for the mother board & 2 small ones, 1 near the cpu heat sink bracket corner & 1 near the gpu heat sink corner. When you lift the mother board out make sure the rams are out & pull the casing near the apple logo towards you as the infrared sensor is located through the apple logo in the front. You basically pull the casing just a bit to flex it so that sensor does not get stuck when you are pulling the motherboard out as its located on the motherboard. There is also a clip holding that sensor, so you can also unclip it, which took me sometime to guess. Its a simple clip so no worries. That sensor also has a cable connected to the mother board.

Before you lift the motherboard off, raise it a bit, as beneath it you will find again a couple of cables including the power supply & SATA for the HDD & DVD drive. Once out you will have to unscrew 4 screws that hold the heatsink. there are 2 sticker (warr void, blah blah blah!!!) on one of the screw (one front & one back) once you take them off for sure you cannot lie to apple as the stickers are plain white but turn into a web pattern once you take it off.

Unlock the lever holding the cpu & you are done. It is socket 1156, so check your dell one first. Be careful as the pins for these sockets are on the socket itself & not on the cpu, well even if you buy any motherboard from outside its the same, you have to be careful with these type of sockets!

Apply heatsink paste after you clean up the old stuff, tighten the 4 heatsink screws evenly & diagonally. Reverse the order of sequence making sure you put back all cables, lastly at the end the ribbon cable for the monitor is delicate so be careful! I needed no BIOS update (macs dont have a BIOS) everything works fine.

If you have not built computers dont try it, or if you are handy do it but be extra careful. I have been building computers for 15 years (as a hobby) & this is no different than opening up a laptop etc. or any type of other electronics.

Just be careful thats all, I can do it quite quickly now as I have opened it up twice now & know what to do!

Good luck!
2 Hours? Um, I took apart the iMac and removed the optical drive, replaced the hard drive and cleaned the heatsink + put AS5 on the CPU and GPU within an hour.

If you're handy, it shouldn't take long at all.
 

cat3600

macrumors newbie
Apr 7, 2010
27
0
Well cleaning the glass & making sure no dust or debris is there, all the wires look exactly the same as it came from the factory, leaving no fingerprints, I wear gloves etc etc. Besides this is not a race, I like to do things perfectly, I am a perfectionist & for a person who might not be too handy (like the thread originator) 2 hours is very plausible.

Ever been to a car dealership where the mechanics are always in a hurry especially for warranty work (as the manufacturer has fixed labour time) I always have to come back to get it right again. I also know boutique garages where they mod cars & know cars, when i get my work done there they take there time & get it done right!
 

Heilage

macrumors 68030
May 1, 2009
2,592
0
If you're handy, it shouldn't take long at all.
Correct. At least to some degree. My first job on a 27-inch was a rear housing swap, which took me three to four hours to complete, but once you get to know the components you shouldn't use much more than an hour on any component swap (depending on which one, of course. Some are far more intricate than others).
 

Mackilroy

macrumors 68040
Jun 29, 2006
3,614
58
Just to point out, the i7 860 goes with the 1156 motherboard. It's the 920 and 930 that are 1336 processors.
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
All of the Intel iMacs have used socketed processors. Not that it's a fun job installing a new one in the iMac.

It's four screws and a latch to replace the processor in my tower. The CPU fan/heatink and thermal paste are the most annoying part to be honest.
Ahh okay, thanks for correcting me. They use laptop parts anyway (socket P) so finding new CPUs isn't easy or cheap so it isn't worth it anyway.

Boxed versions have the thermal already (if you use the fan that comes with it) so IMO it's not that annoying, just put it in and put the fan on top of it and tighten the screws that's all. It sucks if you haven't put the cables in order though. Installing CPU is very straight forward and takes less than 5min but the cable hell is another thing which I hate a lot
 

joudbren

macrumors regular
Apr 13, 2007
244
1
Edmonton, Alberta, Canada
Cat3600, thanks for posting on your successful surgery. I'll probably do this myself when I get a little closer to the warranty expiring and I've been building PC's for over 25 years so pretty sure I can pull this off! ;)

As is, my i5 is the fastest rig I've ever owned and has more than enough horsepower for now but I figure by October the price of an i7 860 should be down closer to the $200 range. Right now in Canada I can get that cpu for $299 so it's already dropped quite a bit over the last few months.

I'll probably throw in a 2TB or bigger HD at the same time as well. I do have a question though... anyone know if the new i7 870 will work in the 27"? It's ridiculously overpriced at the moment ($600+) but it will come down sooner or later. Wondering if the case and heatsink can deal with a CPU running at 2.93Ghz that can turbo up to 3.6Ghz. It is also a socket 1156 in case anyone was wondering. I'll probably not do that one as it will in all likelihood be too expensive for not much of a horse power gain over the 860 but still curious. Cheers!

P.S. Cat, how did you make sure there was no lint or grit on the LCD screen and the backside of the glass when you re-installed the glass? That would make me nuts. Thanks!

James
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
anyone know if the new i7 870 will work in the 27"? It's ridiculously overpriced at the moment ($600+) but it will come down sooner or later. Wondering if the case and heatsink can deal with a CPU running at 2.93Ghz that can turbo up to 3.6Ghz. It is also a socket 1156
It uses the same socket and has the same 95W TDP as 860 so yea, it should. There may be faster 1156 CPUs in future too.