How do I install a CPU with the heatsink already on top?

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Hi everybody,

Today I wanted to add another harddrive to my computer, and decided to
blow out the accumulated dust inside the computer at the same time.

After opening the case, I noticed there was a lot of dust under the CPU
fan, in between the blades of the heatsink. There's a bracket, keeping
the fan on top of the heatsink (or so I thought) so I removed it... and
removed ventilator, heatsink and CPU in one go. Before I knew it, I was
holding the entire block in my hands.

The problem is: I don't know how to place the CPU back on it's socket!

The socket has a handle, which you open to place a new CPU, then close,
after which you can add the heatsink etc... But at this time, the
heatsink is already on the CPU, and I can't open the handle (or leave it
open) with the heatsink on top, so I can't put in the CPU.

I tried pushing a little bit harder, but decided not to use too much
force - if it doesn't move easily, I'll probably break it by using too
much force.

You can see my problem on the following page: -

It's not the same processor, but the socket is exactly the same, and the
entire assembly in figure 10 is exactly the same as well.

By now I'm guessing I need to:
- remove the heatsink from the CPU
- put the CPU back in it's socket (like you do in a new installation)
- reattach the heatsink with new thermal grease
- never touch those brackets again...

Or is there another way to reattach my CPU?

Thanks in advance!


Re: How do I install a CPU with the heatsink already on top?

Ikke wrote:
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You won't be able to close the arm on the ZIF socket, if you leave
the whole assembly together as you describe it (CPU "stuck" to bottom
of heatsink). To do it right, with no risk to the CPU pins (which
can be busted off), you'll have to follow the procedure you

ZIF grips loosely enough, to allow a CPU to be pulled from between
the socket contacts. But once removed, the socket contacts are
closed together. You can't "ram" the assembly back into the holes,
until the ZIF arm is in the open position. And then, once the
heatsink gets in the way, you won't be able to close the arm. The
heatsink would have to be pretty tiny, to leave room for the
ZIF arm to work. Any decent sized heatsink would cover everything.

The original thermal interface material can be a grease, or
it can be a phase change material. For one CPU I worked on,
I had to scrape the material off the surfaces, as I wasn't
making enough progress with isopropyl alcohol alone. So
it'll depend on the nature of the material, as to how
much trouble it'll be to clean up. In any case, don't
get any of that thermal interface material on the pins
or in the socket holes.


Re: How do I install a CPU with the heatsink already on top?

Jan Alter
Quoted text here. Click to load it

By now I'm guessing I need to:
- remove the heatsink from the CPU
- put the CPU back in it's socket (like you do in a new installation)
- reattach the heatsink with new thermal grease
- never touch those brackets again...

You hit it exactly. You can get new heat sink compound at Radio Shack or any
computer repair store or over the Internet.

Removing the cpu from the heatsink can best be done by the use of a pen
knife blade leveraged between the cpu and the heatsink.
For myself I would try an exacto blade, because it's quite thin, but there
is a distinct chance of it breaking if the compound does not release easily.
So careful use of a pen knife should do the trick. Be careful not to touch
the pins on the cpu, and once off you can remove the old compound with
isopropyl alcohol.
If you have need to ever remove a cpu from a cpu again run the computer for
15 minutes or so to heat up the processor first. That should soften the
compound so it allows easier removal of the heatsink from the cpu.

Re: How do I install a CPU with the heatsink already on top?

<snip />

Thanks everyone for your advice - since I didn't have any thermal grease at
hand, I decided to take the computer with me to the dealer.

There, he suggested to do the job for me, since I wasn't successful in
removing the CPU from the heatsink. Took him about five minutes, no charge.
Now that's great service!

Anyway, thanks again!


Re: How do I install a CPU with the heatsink already on top?

On 10/28/2010 4:47 PM, Ikke wrote:
Quoted text here. Click to load it

First remove the CPU from the heatsink. This is often easier said than done
(this might help ) and then
clean both CPU and heatsink to remove all traces of the compound then plug
in the CPU and lock it down then properly apply new heatsink compound --
not too much, not too little (this might help ) and then re-install the
heatsink onto the CPU/motherboard. It can be intimidating the first time
but it really is very easy and safe if you are careful. BTW: inspect the
CPU before installing it -- old ones had pins which could be bent and that
is BAD NEWS while newer ones just have little metal bumps which are much
more forgiving.

Re: How do I install a CPU with the heatsink already on top?

Ikke wrote:

Quoted text here. Click to load it

It appears someone installed an oversized HSF (heatsink+fan) in place of
the stock HSF (if it was a retail CPU purchase versus an OEM purchase
where the buyer had to get a separate HSF).  If the ZIF arm cannot be
moved now that the assembly is out of the socket then just how did you
get it out in the first place?  A ZIF socket grabs onto the pins by
friction but it requires some decent force to overcome that friction on
all those pins to yank the CPU out without raising the ZIF retainer arm.
Don't be so forceful when demolishing, er, dismantling electronics.

So have you been applying anti-static measures when putzing around
inside your computer case and while handling the fan+HSF+CPU assembly?
I suspect not.

If the prior user/jobber used thermal adhesive (glue) then you will have
a very hard time separating the heatsink from the CPU without damaging
the CPU's cover plate, and then you'll have a tough time removing the
glue residue.  See .  It
shouldn't be used for a HSF on a CPU.

If the prior user/jobber used thermal pads, they're like double-sided
sticky tape.  Use a safety razor blade to slide through the foam (which
gets squashed when the heatsink is pressured onto the CPU cover plate).
Then use the blade to scrape off the residue.  I haven't used these
cheap but easy-to-use-for-end-users thermal pads so I'm not sure if a
particular solvent helps remove the residue.  Don't use GooGone or
Orange Clean since those are citrus based and leave behind oils that you
have to clean off very thoroughly.  Something like GoofOff (xylene) or
acetone might work.  Because these attacks various plastics, don't
splash it on.  Use a wetted cotton swab (paper stem, not plastic) to
apply an amount needed to dissolve what you are working on.  Some
suggest using a (old and unwanted) credit card or other stiff plastic
but obviously not a good idea if they are attacked by the solvent you
are using.  Maybe even rubbing with your fingers could roll off the
thermal pad remnants.  Whatever you use, follow with isopropyl alcohol
(not rubbing, wood, or methyl alcohol that leave their own residue) to
complete the cleanup.  In fact, before using the hard solvents, just see
if isopropyl alcohol will work to soften and remove the old thermal
paste or pad.  Lots of CPUs come with the thermal pad pre-installed.
It's not a great choice but okay if you're not overclocking or a fanatic
looking for lowest operating temperatures despite the actual much higher
operating temperature range for the device.  See (computing).

If its cheap-grade thermal paste (grease), it might've dried out and act
like glue.  It will be hard to pry apart and scrape off.  The safety
blade, blade from a utility knife, or shoving in a credit card might
help break up the old dried grease.  Afterward, clean and use a decent
thermal paste.  Did you get any for the reassembly?

An air duster would've eliminated the dust that accumulated on the fins
of the heatsink along with any dust bunnies under the fan blades and
atop the heatsink.  If you're talking about the dust stuck to the fan
blades themselves then you use cotton ear swabs to wipe both sides of
the blades to remove and loosen the dust to then blow off the remainder.
There was no reason for you to remove the fan, heatsink, and CPU to dust
them.  If the dust couldn't be blown out from the heatsink (normally the
only method that should be used) then you have a problem in your
household, like you smoke and the sticky residue from your smoke gets
onto everything: in your hair, on your teeth, in your clothes, on your
keyboard, inside your monitor, and inside the CPU case.  That shit acts
like glue and you'll have to use solvent to get it off.  An air duster
won't work.  Another reason to stop the filthy habit.  Of course, maybe
you're a hair fanatic and load on gobs of hairspray with the overspray
sticking everywhere else.  Think about your environment and why that
dust simply won't blow off with an air can.  Of course, it isn't just
the CPU's heatsink that has that dust stuck on with some gooey residue.
It's on your motherboard, RAM sticks, and everywhere else.  Dust is a
thermal insulator which means heat won't pass through it well and all
your components are running hotter.

Start investigating why that dust got stuck and won't blow off.  It will
coat more than just the HSF inside your computer case.

Re: How do I install a CPU with the heatsink already on top?

Quoted text here. Click to load it

Do exactly what you just typed above.

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