Installing CPU

When installing a CPU (for example, upgrade, new build, or replacing) is it better to carry out the CPU placement, and mounting of heatsink with consequent tightening of levers or screws with the m/b mounted inside the case, or outside the case ?

Dumb_Question
24.October.2013
socket 478

 

Best done outside, although some cases do allow access through a panel hole to the rear of the 'board.

 

Thanks for your answer, satrow. It makes sense that everything is more accessible with the m/b free standing and outside the case.

I don't understand your tail comment "though some cases...". All cases allow access through a large hole where the side panel lives, don't they ? In my PCs the m/b and CPU mounted in the plane of this panel as in the illustrations found here I would have thought that maybe there is enough room in the case to allow mounting from the vertical position ?

my question was asked from the point of view of the stresses that are on the m/b when mounting the CPU on the free standing m/b, or on the m/b while also pre-stressed (or supported by) by the pillars on which the m/b sits in the case.

Dumb_Question
24.October.2013
socket 478

 

I always insert the CPU and RAM with the motherboard out of the case and if it is brand new I have it sitting on top the anti static bag on top of a sheet of the motherboard packing foam.
My Lian Li cases have a removable panel that slide out the back with the motherboard attached so I mount the motherboard on the panel outside the case then mount the standard heatsink with clips and slide it back in the case. If it is an aftermarket heatsink and has a plate needing to go on the back of the motherboard then in my case you need to do this with the motherboard unmounted out of the case.

In all my cleverness I didn't figure out that my groovy removable panels can only be used effectively if I use a standard CPU heatsink rolleyes Because I overclock I actually use the Noctua NH-D14 and it is so big that it won't fit through the hole so it makes my removable case panel feature useless

 

I tried to edit this onto my previous post as I didn't cut and paste it from the editor when I originally posted and then I closed the editor DOH!
So I did it again

@Dumb_Question
My Lian Li cases have a solid unremovable side behind the motherboard so the only access to the rear of the motherboard is via the slide out mounting tray to the rear. My problem comes when I don't use a standard CPU heatsink and the heatsink I choose is much bigger than the opening meaning I can't slide the tray and motherboard back into the case.
re: motherboard stresses
If the heatsink is applied when the PCB is nice and flat (no bows) and then the motherboard is mounted in the case flat and screwed down to all the posts then there shouldn't be a problem. Modern multilayer PCBs are remarkably robust thanks to improvements in polymer technology and modern protective coatings. My previous job was Head of the PCB Design Department in R & D for a major electronics corporation and having designed countless multilayer PCBs I can assure you that if treated carefully PCBs are very reliable.
Of course it is not advisable to bend or twist them and they don't like getting too hot (can delaminate) and as with all electrical equipment they don't like conductive fluids spilled on them. Another thing to note is that most surfacemount components are quite small and the board shouldn't be able to flex sharply enough to compromise the solder joints or strength of the component. Some large Quad LSI (large scale integration) chips have a small amount of give in the component leads to mitigate the problem of flexure over a broader area thus reducing failure of the solder joint or fracture of the pad connection due to bending.

Hope this helps

 

It does not matter. On new builds, I install the CPU, HSF assembly, and RAM outside the case. On upgrades, inside the case (if I have access to the back of the board - if required). The most important part is don't connect the PSU, don't touch the CPU or socket contacts, discharge static in your body, and make sure you thoroughly clean the mating surfaces (if necessary) and apply a proper layer of TIM (thermal interface material).

That said, on HTPC builds with very small cases, it is often impossible (for me) to have my hands inside the case and be able to see what I am doing. So in some cases (computer and situations) taking the board out of the case is simply necessary just to see what I am doing.