Has anyone lapped their P4 Northwood heat spreader ?

[Cuke]

It seems to me, if I'm going to the trouble of lapping my Sunflower's
copper core to a morror finish, I would want the same (or nearly)
for the "mating" surface (ie: the CPU's heatspreader).

What about that hole in the Northwood's heat spreader cover?

I figgered if I start with 600 grit, moist (not soaking), I can
minimize the risk of getting metal shavings (dust) and/or water
inside.


I think it's safe to assume I'd have a difficult time obtaining warranty
service on a CPU that is not only "modified", but no longer identifiable,
should the future need arise. (tho the need has never arisen with the
last 6-8 cpu's I've purchased)

Has anyone here lapped their Woody?
Could you share your experiences?

Thanks !

 

[bacillus]

if you're serious then it's best to completely remove the spreader & expose the core slug!
you'll have one less interface for the heat to go thru.

 

[EdipisReks]

my 1.6a is a beautiful copper mirror. i'm just waiting for my replacement motherboard to get here (the first one was a dud). i briefly ran my CPU before i lapped and then afterwards on a friends system, and i got a 9*c reduction at idle and a 7*c reduction at load at 2.133 gHz with default voltage. the IHS was really uneven. before i lapped it, my pentium 4 was only getting good contact at the edges. removing the heat spreader is an option, but it is a little too risky for my taste.

to acheive a good surface, do the following: 1. buy a piece of glass and packs of 320, 600, 100, and 1500 grit wet/dry sandpaper. 2. tape the sand paper to the glass. 3. put a piece of anti static foam over the pins of the processor. 4.put a little water on the sandpaper. 5. sand the processor using gentle circles, being careful to put even pressure on the processor. progress through each grade until you are satisfied. 6. burnish it with the back of a piece of sand paper. easy process that takes about 30 minutes.

[edit: don't worry about the little hole.]

--jacob

 

[THUGSROOK]

i agree with bacillus - lapping will be a waste, remove the heatspreader.

 

[Cuke]

<< if you're serious then it's best to completely remove the spreader & expose the core slug!
you'll have one less interface for the heat to go thru. >>



Is that spreader removable ??? I thot it was "glued" down!

What other dangers may lurk below the spreader?
I've never "modded" a cpu before (nor lapped a heatsink, for that matter)

Would I need to lap the core slug?

Are there conductive and/or fragile parts (ie: bond wires) I'd need to
watch out for?

 

[THUGSROOK]

i remember seeing a pic of one removed at HOCP. it looks pretty much like a p3 core under there. nothing special.
there have been some reports of them "falling off" on older s423s so they may not be stuck on too tightly.
id rip mine off but i dont have any heat problems on my 1.8A - 42*C max w/1.7v.

 

[EdipisReks]

i wouldn't take off the heat spreader. i know someone who cracked the core taking the ihs off of a northwood, and someone else who crushed the exposed core of a socket 423 PIV with a heatsink. lapping is certainly not a waste of time. it is a pretty popular past time over at the hardforum. frankly, removing the heat spreader gets rid of part of the point of getting a pentium IV: you can't damage the core because of the heat spreader.

--jacob

 

[F155mph]

 

[Dink]

Mine's lapped. Got a 3c drop in load. I'm at 36c at load now water cooled. 1.6a@2240

 

[Cuke]

EdipisReks: Thx for your info. I had decided to leave it alone for now, figuring
I could lap it later, if it seemed I might need to, but I changed my mind and
spent my lunch hour today getting it done.

First, I recorded all the info printed on the heat spreader, then I found a nice piece of
optical grade glass (the platen from an old flatbed scanner)

I had sheets of 400, 600, 1000, and 2000 paper left over from lapping my sunflower.

Since the P4 spreader LOOKED good and flat, I tried starting off with the 1000, but
THAT was a mistake; I soon dropped down to 600, then 400. It seems that whatever
the "silvery" metal is that's plated over the spreader (tin?, aluminum?) is tougher
(harder to sand) than the soft copper lying underneath.

I found that the center of the spreader was the high spot, followed by the edges. The
area between the edges and the centertook the longest to get the plating off.

After about an hour total I got my "copper mirror" using all the grits mentioned above.
I like your idea of "burnishing" with the backside of a piece of sandpaper. It worked
nearly as well as the Mother's Mag wheel polish I used on my sunflower, without
getting any polish goop up into the heat spreader's hole.

I did get a couple of coppery colored drops of water out of the hole when I was finished.
Do you think that's OK, or should I try washing out under there with some alcohol or
something?

Hopefully, I'll be getting this rig put together sometime this weekend.

P4 1.6A Northwood Costa Rica, lapped
AVC Sunflower (or PCP&C lookalike)
Asus P4S333
MSI Geforce3Ti200 64MB
1 - 512MB PC2100 (generic - ouch) w/ ThermalTake heat spreader.
80 GB Seagate Barracuda IV
WinXP ( $1.50 Malaysian version {see Thugsrook's sig} )

 

[Grendel99]

I wouldn't plug in the chip until you know for SURE it's dry. Maybe let it sit upside down for a day and let it air out.