iMac Pro Processor Socket…

We know that the width of a DDR-4 module is 133 mm. Right? Well. I resized (a snippet of) the image that Apple uses on its website and here it is:
Snippet of Apple provided image
Isn’t that processor cooler heatsink pretty big? It measures almost 8 x 11 cm. A super size for both the LGA2066 and LGA36471 processors. Yeah. I still wonder why it is that big. Is that just to dissipate the heat, or is Apple really going to use a LGA36471 socket/processor?

Now look at that chip/print below it. What is that? The first time that I looked at the image, I immediately thought about some sort of Intel Fabric Passive (IFP). Something you see on Knights Landing Processors wherw a Wolf River Fabric is used (on supported modules).

I am probably wrong, and yes it supports six memory channels (max). Compared to four for LGA2066 processors, but none of them supports ECC memory. And there is no need to use all six channels. Four is enough, be it slightly slower.

What do you think?

Update: No. Sorry Pike. Apple is not going to use the LGA3647-1. It’s just to big to fit underneath the two heat pipes. However. The LGA2066 is 45 mm x 52.5 mm. A much better fit.

Edit: Also. I went through the firmware. Once again. And the CPUID code to read the brand string does not include checks for the X series SKU (0x55).

Edit-2: Intel confirmed that the iMac has a LGA2066 socket, for the Xeon W-2145 (8C/16T), Xeon W-2155 (10C/20T) and Xeon W-2195 (18C/38T)


4 thoughts on “iMac Pro Processor Socket…

  1. Not sure if I’m misunderstanding your post, but the CPU here is between the DIMMs. It has a block on top of it with heat pipes leading to the heat sink. If you look at the full image, you’ll see two more heat pipes coming from a similar block to the right, which is the GPU. This lets them use a single heatsink for both parts (which is surprising considering the combined TDP of both the Xeon and the Vega is a few hundred Watts.

  2. Would not be surprised to need such huge cooling parts — the higher core LGA2066 CPUs are heat hogs. See here,,5092-11.html, where Toms Hardware had the 7900x hitting thermal limits under stock frequencies. It will be a challenge to keep those cool, I suppose that will in fact be the primary engineering challenge for the new iMac pros.

    I wonder if the Xeon parts will be better on heat (probably), and if they’ll be better on the thermal paste/connection between die and lid, which is what causes the heat here.

    • I can confirm that. I had an Intel i9-7900X (ES) at home for testing, and with my setup. With a water cooler (with four fans). It could not get it under 60 degrees. So yes. The Xeon’s will have to be a lot better in this aspect. And that with only two heat pipes on the processor.

      As always. Good article from Toms Hardware. Thank you for the link.

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