Lapping a P4?

I have a P4 2.4B stepping SL6SH. I was shocked at how rough the heat
spreader is. I mean, it almost looks like it fell off the back of a truck,
and skidded along the road for a mile or two. :-)

The obvious solution is lapping. But I see that there is a small hole in the
heat spreader, and I'm concerned that if I were to lap the heat spreader,
debris would pack into the hole. Worse, there appears to be a very small gap
between the heat spreader and the substrate (?), so the heat spreader seems
to touch the CPU only at the slug. This would mean dust, silica, and metal
shavings could pack in under the heat spreader.

I'd really hate to ruin an expensive CPU, but on the other hand I'd like to
get more than just an extra 330 MHz out of the CPU.

Is lapping the slug advisable? What if debris gets under the slug, will /
may it short out something? What would be good to temporarily plug the hole
in the slug, maybe a very tiny dab of silicone sealant?

--
Tony Sivori

Before you do anything, try running the cpu cooler by collecting the air
from your airconditioner by taping a plastic bag over the outlet, and
ducting the cool air to the cpu fan using a vacume cleaner hose. Check to
see if the lower temperature gives you any extra performance. My guess is
that it won't. So you'll save yourself from defacing your cpu. I've been
down this road with old P4 1.8A. I even removed the IHS totally from my cpu.
In my case, it was a waste of time, but some people report better
temperatures when the IHS is removed.

Once the IHS is removed the chip looks exactly like a coppermine P3 or
Celeron but smaller (if that helps)


"Tony Sivori" wrote in message
...
I have a P4 2.4B stepping SL6SH. I was shocked at how rough the heat
spreader is. I mean, it almost looks like it fell off the back of a truck,
and skidded along the road for a mile or two. :-)

The obvious solution is lapping. But I see that there is a small hole in
the
heat spreader, and I'm concerned that if I were to lap the heat spreader,
debris would pack into the hole. Worse, there appears to be a very small
gap
between the heat spreader and the substrate (?), so the heat spreader
seems
to touch the CPU only at the slug. This would mean dust, silica, and metal
shavings could pack in under the heat spreader.

I'd really hate to ruin an expensive CPU, but on the other hand I'd like
to
get more than just an extra 330 MHz out of the CPU.

Is lapping the slug advisable? What if debris gets under the slug, will /
may it short out something? What would be good to temporarily plug the
hole
in the slug, maybe a very tiny dab of silicone sealant?

--
Tony Sivori

Richard Hopkins wrote:
"Tony Sivori" wrote in message
...

Worse, there appears to be a very small gap between the heat spreader and
the substrate (?), so the heat spreader seems to touch the CPU only at
the slug.

Not quite correct.

This would mean dust, silica, and metal shavings could pack in under
the heat spreader.

No, that won't happen. Round the edge of the IHS is a bead of elastic
bonding agent used to hold the slab to the substrate. That will stop any
crap getting in.

I expressed myself poorly, sorry. I meant there is a gap at the bottom of
that small hole in the heat spreader. The gap is too small to be seen
clearly by naked eye (mine anyway) but I confirmed it by very gently probing
the hole with a dental pick. So was worried about dirt from the lapping
operation packing into the bottom of the hole and then into the gap at the
bottom of the hole.

However, the bond is actually designed to compress under the clamping load
of the heatsink, theoretically allowing the IHS to press firmly against
the core, optimising the thermal bonds. It's most unlikely, but if you
let a large amount of solid crud build up around the edge of the IHS, the
bond could be prevented from compressing, thus making the heat
dissipation worse!

Is lapping the slug advisable?

It ain't gonna do any harm if you do it properly, let's put it that way.
However, if you expect an extra 500MHz out of your CPU, you're likely to
be disappointed.

I'd be happy with another 50 MHz, and delighted with anything more.

What if debris gets under the slug, will / may it short out
something?

Most unlikely.

What would be good to temporarily plug the hole
in the slug, maybe a very tiny dab of silicone sealant?

Yeah, that'd fly. To be honest you could leave it plugged permanently if
you wanted to. The hole is primarily there to allow gases liberated by the
setting sealant to escape. Thus, it's job is really done by the time you
get your grubby mitts on the chip.

That was my next question, what is that hole for anyway. Thanks for
answering it before I even asked.

--
Tony Sivori

John wrote:
Before you do anything, try running the cpu cooler by collecting the air
from your airconditioner by taping a plastic bag over the outlet, and
ducting the cool air to the cpu fan using a vacume cleaner hose. Check to
see if the lower temperature gives you any extra performance. My guess is

Not a bad idea, I'll try it. I'm using the Intel fan and heatsink so there
are better ones available.

--
Tony Sivori

"pete" wrote in message
.com...
This is what I did to lap my 2.0. I packed a small amount of heatsink
compound into the hole so that the hole was sealed flush with the compound
and not allow any foriegn material to get past deep into the hole. Only
enough to close the hole. I proceeded to lap the IHS then sucked the hole
out, with any fine metal particles and compound. Sounds strange but it
worked perfectly.
Been running it fine at 2.66 with stock HSF and voltage. Underload max it
hits 42c. At idle it sits at 30c.

Pete

My 2.4 @ 2.7 is running at 45c no load, and around 55c full load
(seti@home). That is with an Abit board and some say they measure temps
hotter than others.

Overclocking is kind of disappointing; no better than 2745 MHz with memory
at 190 MHz. I tried cutting the memory back to 1:1 so it couldn't be a
factor, and the best I got was 2880 MHz - and that locked up at the log on
screen. At 3.0 GHz, the boot screen stayed black, even though I had boosted
the voltage 10%. At 2800, it ran but was very unstable; frequent program
crashes and some blue screens.

I guess I shouldn't complain, it is one hell of a lot faster than the PIII
650 @ 900 that it is replacing.

--
Tony Sivori

Optonline wrote:
Are you asking if you should lap the heat spreader?

Yes.

No, no, no, you want to remove it. Its a standard flip-chip underneath. I
wished Intel would have just left it alone and not glued that damn hunk of
metal on it.

Here, read this: http://www.overclockers.com/tips1087/

Thanks for the link. I had stopped reading overclockers.com quite some time
back; they had gotten so AMD-centric, and their insistence of referring to
the P4 as "PIV" for some reason annoyed me considerably.

The photos, especially on page 3 were very revealing. It looks like junk
packing into the vent hole of the heat spreader during lapping is a factor,
although not likely to cause damage.

As for removing the heat spreader, between the hazards of the operation and
the increased chance of damage to the core later (when mounting and
unmounting the heatsink) I think I will pass on that for now. I cannot
easily afford to buy a new CPU if things were to go badly wrong.

--
Tony Sivori

Thanks for the link. I had stopped reading overclockers.com quite some time
back; they had gotten so AMD-centric, and their insistence of referring to
the P4 as "PIV" for some reason annoyed me considerably.

The photos, especially on page 3 were very revealing. It looks like junk
packing into the vent hole of the heat spreader during lapping is a factor,
although not likely to cause damage.

As for removing the heat spreader, between the hazards of the operation and
the increased chance of damage to the core later (when mounting and
unmounting the heatsink) I think I will pass on that for now. I cannot
easily afford to buy a new CPU if things were to go badly wrong.

--
Tony Sivori


I found that the surface where the HS faces the CPU is very curved, looking at
it with a magnifing glass i could see where it looks like the outside edges of
the cpu have been cut with a lazer leaving some raised edges. I lapped mine to
the point where the letters were almost gone and the surface was still not
flat. I'm sure you could get it flat but you would remove all the lettering.
I think the thin shim on the cpu is soft enought to conform better to the
heatsink because it it soft. I removed the shim and used some ARTIC silver and
it lowered the temps a few degrees over the Intel pad. DOUG

Thanks for the link. I had stopped reading overclockers.com quite some time
back; they had gotten so AMD-centric, and their insistence of referring to
the P4 as "PIV" for some reason annoyed me considerably.


Yes and the fact that they won't except the fact that the new 800 FSB cpu's
have knocked them off the top..... DOUG

"pete" wrote in message
.com...
I proceeded to lap the IHS then sucked the hole out, with any fine
metal particles and compound. Sounds strange but it worked
perfectly.

?? Bet it tasted funny... ;-)
--


Richard Hopkins
Cardiff, Wales, United Kingdom
(replace .nospam with .com in reply address)

The UK's leading technology reseller www.dabs.com
Out with the old & in with the new at www.dabsxchange.com
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I knew that was coming ; )

"Richard Hopkins" wrote in message
...

"pete" wrote in message
.com...
I proceeded to lap the IHS then sucked the hole out, with any fine
metal particles and compound. Sounds strange but it worked
perfectly.

?? Bet it tasted funny... ;-)
--


Richard Hopkins
Cardiff, Wales, United Kingdom
(replace .nospam with .com in reply address)

The UK's leading technology reseller www.dabs.com
Out with the old & in with the new at www.dabsxchange.com
Get the most out of your digital photos www.dabsxpose.com