The CPU and heatsink should be installed when the motherboard is installed in case.
Tip for all, always wear an anti-static wrist strap as damage by static electricity which you can't see or feel can mean all sorts of random problems or early failure of components in the future. Only handle the motherboard and all components by their edges, don't touch any connections as grease will cause contact problems.
Installing the CPU and Heat sink in the case is not necessary. You can do it in the Mobo box just make sure to wear a grounding strap hooked to the chassis.
I had a problem putting my heat sink onto the mobo. When I installed my heat sink one of the 4 screw holes was slightly misallined. So I had a heck of a time getting it in place.
1 of 1 people found this helpful
Intel's installation guide shows installing the motherboard first. It is because heat-sinks (certainly the retail ones) use a slight flex of the motherboard as a spring to ensure the heat-sink fits firmly, and this is designed to work when the board is screwed and anchored in the case. Also you need space under the board to allow the heat sink fitting pins to push further through as you press the clips, you might not have this clearance with the board in the box or on a flat surface. When you push the clips with the motherboard flat on a surface, you are pushing against the surface (or deforming the box) and not pushing against the motherboard as you should be doing. It is the pushing against the motherboard that ensures a firm fitting.
Installing the motherboard without the added weight and awkwardness of a heat sink attached is also less prone to problems, and avoids the temptation to use the heat sink as a handle to maneuver the motherboard, which could reduce the bond between heat sink and CPU. Also if while fitting you drop the motherboard against the case or screw posts, you are much less likely to damage any copper tracks when the board is lighter from having no heat-sink attached.
It's not necessary to install the CPU or heat-sink while in the case, but certainly the best way to ensure a good install of the most typical retail cooling solutions.
I can see the advantages in installing the cpu in the already installed motherboard. i just finished the build today, it went smooth!
Thanks for the answers!
M. R. Maack
Your welcome even if you didn't install the way I suggested. In the computer world there are many ways to do things.
I hope you enjoy your new build.