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Removing and replacing heat sink: sequence of screws
For multiple laptop models, Dell's service manuals say something like this:
Removal
"In sequential order (indicated on the heat sink), loosen the seven captive screws that secure the heat sink to the system board".
Replacement
"Align the seven captive screws on the heat sink with the screw holes on the system board and tighten the screws in sequential order (indicated on the heat sink)."
The sequence is identical. Logically, I would have expected that replacement should tighten screws in reverse sequence from the removal sequence. What's the reason for using the same sequence for each procedure?
Dell-Brad L
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October 4th, 2022 11:00
This can vary on the model, but here's an example at this link of an XPS 9520 doing reverse sequential order in the removal section (for example remove screws in order from 4 to 1), whereas under the install section of this model you install it in the normal order 1 to 4.
Do you have a model showing this same order?
In my experience remaining consistent on the order for removal per manual is what's more important (since these shouldn't have a crazy amount of torque etc.) and also making sure the processor/heatsink has been cleaned thoroughly before reapplying thermal paste/reinstalling.
For example, if I notice it's a system where the heatsink might have been torqued down a bit too much by a previous tech, I like to back off a little on each screw in order so the tension is reduced and more evenly distributed (this really varies on what I come across, but hasn't impacted removal of any heatsinks in my personal experience), and then I will follow the specified removal sequence fully removing each one.
When putting a heatsink back on, again in my opinion/experience over the years, I like to at least get each screw threaded in a little bit, and then do the order so the tension is more evenly placed. Using this method seems to make it a little easier, especially if there is a lot of tension/you notice screws moving (again this depends on heatsink design).
Here is a link from Intel on how I personally install heatsinks (I realize this is for a desktop, but it's still helpful), ie I will tighten each screw to at least get them started (and will stop before any real tension, so on an XPS in order 1-4) and then go back over and actually tighten them again in order, using this method over the years I always seem to have great results on thermal temps/no damaged parts. I really prefer the pressure on the chip to be applied as evenly as possible vs some designs where it becomes really hard to do that if one screw is fully tightened down.
filbert
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October 4th, 2022 12:00
Two I worked on recently: Inspiron M4040/14-N4050 and XPS 15 L502X. I realize they're quite old, they just happen to be the ones I looked at lately. I know I've also seen service manuals for more recent models that did not specify reversing the sequence.
I agree with you. That's a good practice not only for heat sinks, but also for many mated assemblies in appliances, automotive, etc.
Thanks for the reply and your input.
Dell-Brad L
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October 4th, 2022 13:00
Yes! I do the same thing on all kinds of repairs, especially anything that is going to be exact/to spec and have a high torque like a head gasket etc. And yes, very good practice that applies to pretty much everything. Makes repairs go a lot faster!
I am also seeing what I can find on the models you shared.