Lapping CPU heatsink

Hi everyone,

While I was waiting for my batteries to my digital camera to charge (was writing a review about the notebook) I decided to tear it apart(This is a HP ZX5000 with a P4 3.0HT). I pulled the plastic piece off the back to reveal the two fans, which i then tore the shrouds off of. I inspected them and decided there was no mods I wanted to do to them and moved on.

I then unscrewed the heatsink and dual heatpipe cooler from the cpu. It came off easily, just needed some wiggling. The cooler is L shaped with a radiator on each end(one fan in back,one on the side) with the CPU being at the center of the L. The surface of the heatsink was _very_ scratched and uneven, especially right over the core.

I decided to lap it.

I ran the heatsink over 400 grit with soap and water 10 times each then rotated it 90 degrees, until I had made about 5 rotations(50 strokes or so in each direction) then I repeated the process with 600, 1000, 1500 and finally 2000 grit sand paper. By the time I was finished the heatsink was mirror shiny and I was very impressed. I cleaned the CPU off with isoprophyl as best I could and applied Artic Silver to the heatsink, then wiped it off so it was left discolored(left only what stuck in the tiny grooves) Then I applied about 1/2 BB size drop to the P4 and applied the heatsink, tightening the screws in a clockwise manner. The screws are springed so they apply the correct pressure once you have them turned in to the premade limit. Im using it right now and for the first time I can do things with just one of the two fans running, and rarely does the second kick in. A definite difference! Unfortunately when I installed MBM5 I found out this MB doesnt have on the board sensors, so I cant give an exact temp change. If anyone has a place to host pics I can upload a few I took of the heatsink before & after, and the P4 mounting setup.

 

At first I though you were really sick, but it probably helps a lot with noise to not have that fan kick on. Nice project! If you feel like writing a how-to, we're happy to post it with pictures in our main news section.

Editor in Chief http://www.bargainPDA.com and http://www.SPOTstop.com

 

Nice job with that, I'm glad to hear it worked out. Inspiron 8600 owners arent the only ones who can do heat-mods[ ]

GPU cooling (100°C->75°C)* Inspiron 8600 * 1.8ghz Pentium M * 128 MB Radeon 9600 Pro Turbo (337/242 -> 400/300) * 2x512 MB DDR2700 SDRAM * Aquamark 3: 24058 * 3DMark'03: 3404 * 3DMark'01 SE: 13120

 

I don't remember if MobileMeter works with the zx5000 series or not, but give it a try.

Nice mod. I'll have to go find that good sandpaper. I won't use it until I'm ready to swap in a faster CPU though, since I have a zv5000z and have found that undervolting the Athlon 64 CPU is amazingly effective at preventing heat from being generated in the first place. Your P4 can't do that though [ ][ ]. Still, every advantage helps. I just wish there was a way to shut the fans off entirely.

 

Hey! it does work, awesome. Thanks a lot for that program.

Idles at 37C load is 52C.

My desktop is 27C idle and 37C load hrmm. Too bad I didnt have a measurement before i lapped the heatsink.

Anyone else have a zx5000 that can give us some temps stock?

Edit: How crazy would I be to lap the heatspreader on the P4 itself? Also I have been thinking about modding the fan grills on the bottom, they seem very restrictive... im thinking cut them out with a dremel and buy some chrome 40mm or so fan grills to put on there? Does anyone know if its possible to mod the bios to change when fans go on and off?

Also I have this floppy bay right above the DVD Drive that i didnt get the drive for... so as far as I know its empty space atm, and im thinking of what to put in it.. hmm.. if only HP made a subwoofer that went in that bay!

 

I believe my desktop is accurate. It is liquid cooled, and water has a much higher thermal conductivity then air. Also, my temps of 37-52 might not even be in the same playing field as yours, im in an air conditioned house atm and its fairly cool in here. Under normal temps its more likely to be 40ish-to-60ish. Ive been working on underclocking this P4, I'll let you know how it goes.

Its very tempting to lap the P4 after seeing it... drop me a mail at:

[email protected]

And I can attach some pictures of the P4 and lapped heat sink if you want to see what im talking about.

Matt

 

What's important is the difference between idle and load. A 15C diff (52 - 37) on a laptop is very good, excellent really given what a pig the P4 is. Your desktop is probably underreporting its true temperature (that happens a lot), but its 10C diff is probably accurate. FWIW, my zv5000z idles at 37C too, and that's while running 1GHz at 0.85V (maybe a dozen watts power consumption, I don't know how to measure that).

I wouldn't attempt to lap the CPU. You've already achieved most of the gain you're likely to get.

 

Just read this and applied arcticsilver 5 to my hp pavilion zx5000 notebook, it also runs the radeon 9600 card in it. I had the same heatsink and pentium 4 3.0 HT processor but I didn't notice much of scratches/grooves on the heatsink so I did no sanding. Used 91% isopropyl to clean both heatsink and processor of any paste. I applied almost an entire BB of paste in the center, probably to much.

Thus far, all of 20 minutes later, playing games (hl-2 counterstrike), the fan(s) kicked on after a much longer wait, and generally feels as though is running cooler. I'll report back after getting some temperature gauge software and i may re-apply with less arcticsilver.

Thanks for writing this thread, I figure the arctic silver stuff will probably do more good than buying one of those laptop cool plates at best buy.

 

Hey, nice mod.

I'd be guessing that the new thermal compound is making most of the improvement, lapping heatsinks is rapidly approaching the point of diminishing returns... however, if you have the time and elbow grease for it, more power to you.