I have this same issue. Repasted it, both fans spitting out cool air out the back at 6200RPMs with Macs Fan Control. I replaced the heat sink with a used one from Ifixit, which brought the laptop some benefit as the heat gets to the near edge of the fin stacks, but no further. Do I need to get a third heat sink??
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=== Update (10/06/24) ===
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@danj thank you for your time! Here are some screenshots. Not even crazy CPU usage, just things like opening a tab or two or taking a screenshot will crank the temps. It gets and stays hotter than my 9,1 Unibody MBP (same i7-3615QM and GT650m) but not all the heatsink gets saturated with heat, unlike the 9,1.
I have this same issue. Repasted it, both fans spitting out cool air out the back at 6200RPMs with Macs Fan Control. I replaced the heat sink with a used one from Ifixit, which brought the laptop some benefit as the heat gets to the near edge of the fin stacks, but no further. Do I need to get a third heat sink??