Are you sure you have correctly identified the CPU & GPU?
There is a heat sink that lays across the chips with thermal paste between. Review this IFIXIT guide: [guide|10293|MacBook Pro 15" Retina Display Mid 2012 Heat Sink Replacement].
Please post a good hires picture here if you have something different.
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== Update ==
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This grey stuff is the thermal paste. This is critical in controlling the CPU's & GPU's temperature.
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I strongly recommend you clean the chips of what's left and apply a clean coat of a good quality paste.
Once you break the bonding between the chip and the heat sink as you have here, you will loose the efficiency of the heat transfer. Basically, you will burnout the chips as they can't dissipate the heat properly if you stick the heat sink back on now.
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Follow this IFIXIT guide on the proper way to clean & re-apply the paste: [http://www.ifixit.com/Guide/Applying+Thermal+Paste/744|Technique: Applying Thermal Paste]
Are you sure you have correctly identified the CPU & GPU?
There is a heat sink that lays across the chips with thermal paste between. Review this IFIXIT guide: [guide|10293|MacBook Pro 15" Retina Display Mid 2012 Heat Sink Replacement].
Please post a good hires picture here if you have something different.