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Bryon H
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ibm power 720 server, how to remove heatsink

Ok i'm stumped and google/youtube are no help in this case

how exactly do i remove the processor heat sink on this server?
Server HardwareIBM System i

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Mike Castro

8/22/2022 - Mon

A read through this


suggests that removing the CPU and Heat sink is not a user replaceable part. If the server has value to you (that is, you want it to work) then get IBM Support to service it.
Bryon H

Thanks for the suggestion - the server is of no value anymore other than resale of parts...  on its way to being recycled... these two pieces would be great for resale

So then with some mechanical acumen, start unscrewing bolts and screws to see if you can loosen the part. If there is a solder joint (appears there might be) you would need a heavy duty soldering iron or gun to provide enough heat for long enough to loosen.

Put a screwdriver underneath and very gently pry. See what moves and work there.
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Bryon H

Good suggestion - working that angle now.  Have the board out, but it's secured to a similar sized piece of metal supporting the entire board from underneath, secured by screws from under the heatsink (cant remove the metal tray)

Seeing closer, the mechanics appear to suggest if i move the cross bar down, the hinge brackets would be able to move off those bars - but it takes an incredible amount of pressure to even budge it...  hoping there's something easier like - insert here, pry there

Closer pics - it looks like i should be able to just force the vertical brackets back away from the sink and they'd unhook?

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Bryon H

Found an interesting hex screw directly down the center hole from the top of the sink, locked into it with a bit driver but no amount of force seems to even budge it (probably under immense pressure from the clamp)

It is hard to imagine from the pictures but the clampdown is likely to prevent loosening under fan vibrations.  

Does the screw turn in the opposite direction for some strange reason?
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Bryon H

Success - just bit the bullet and pried between the horizontal bar the clam was on, and the clamp itself - with outward pressure, snapped right off no damage

interestingly there's not a  spec of thermal paste between the sink and the cpu, first time i've seen that - but then again this is the first ibm power as400 whatever this is i've had

Thanks for the update and I was most happy to work with you even from the pictures
Mike Castro

Sorry for reviving a 6~7 month old thread, but...

The Power720 is an AS/400 great-great grandson (so to speak)... a 7 year old server which still has quite some computing horsepower even nowadays. It runs PowerLinux (SLES 11 SP4, Fedora 27, etc.), AIX and IBM i. It's a Big Endian machine. I have a Power 720 and a 740 and they absolutely rock with databases (PostgreSQL, etc.)

Anyways, as someone stated before, the heatsink has a hole down the center and there is a hex-screw which clamps down the heatsink to the retainer. You need quite some force (counter-clockwise) to loosen it. The heatsink then just comes right off.

As for the TIM (thermal paste), there is none, as you have observed. Instead, there is a square piece of TIM (soft-aluminum type) pasted on to the massive heatsink which interacts with the heatspeader on the Power7 CPU.

As I have also removed my CPU for routine thorough cleaning, I have peeled this TIM off (since maybe it would not be effective anymore once the heatsink is removed) and replaced with Arctic Silver 5 when I re-assembled.
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