Legit Reviews

Would 600G sandpaper alone be sufficient enough for lapping a P4?

It will help but you really want to go up to 2000. sand paper is not that expencive i got paper ranging from 400 - 2000 for ~ $8

600G is a bit too rough still... I'd go much smoother

http://www.easypckits.com
You can try this one, i have and found it to be very nice, comes with very good directions, a piece of glass (for perfectly flat surface, and a great variety of paper), or you can go to your local hardware store and get some wet/dry paper from the autobody section (they usually carry up to 1500-2000 grit)

http://www.easypckits.com/products/premiumlk/
While reasonable priced, if you take your $13 plus shipping down to the hardware store, you'll end up with a much bigger selection of lapping supplies.
The "shiny-ness" is not nearly as important as flatness and his instruction PDF is a good guide
http://www.easypckits.com/faq/premium.pdf

For that $13 you are also getting the whole kit (I have yet to see a store carry "micron" grade paper) and at least one tube of thermal paste, I got a tube of AS Ceramique and a tube of AS 5. though i agree and thought I pointed out that the DIY way was cheaper.

How much difference does lapping make? I know this can vary greatly from one system to the next but would you say it helps a lot or a little, on average?

Personally it made about 5C difference on my 3.2E, part of that was a poor base on the heatsink, part of it was a very uneven cpu heat spreader. You can get a good idea of the flatness by making a few small passes over some fine paper. you will see sanding marks where there is contact. After doing this for a minute or two on a flat surface you will be able to tell how flat your CPU heat spreader is. Same with the heat sink base, alot of times you will see grinding grooves on the base, sometimes you can feel them by running a fingernail over them sometimes they are alot more subtle.
But even small amounts of unevenness (is that even a word) make a differeence when transfering heat from the CPU to the heatsink

unevenness @ Dictonary.com

Looks like a valid word to me!

Like capper said most people, including me, find that lapping can improve things upto ~5c. When i lapped my heatsink i got an average of ~3c lower on my tempretures.

So you lap the heatsink and the CPU? I had understood that you should use wet paper but I gather that is an absolute no no on the CPU so what do you use there to keep things smooth and keep the particles from getting where you don't want them? My temps are pretty good now that I got a SLK900 heatsink and a 92mm fan but a few more degrees off the load temp is worth some effort as long as its not easily messed up.

I used denatured alcohol to clean the sandpaper every few minutes. Do not use water. with the CPU. when i was finished, i cleaned the heat spreader with "Goof Off" came out very nice. It is worth the trouble, but be very careful.
If you are happy with your temps, don't mess with it, or just lap the heat sink. There is too much that can happen (bent pins) by messing with the heat spreader on the CPU, when i did it my butt was puckered the whole time. ..... I was thinking about damaging a $350 CPU.

I know it may seem odd, but you might want to pick up a spare socket. Some stores sell them online and they range in price from $1-$5. With an extra socket laying around you can lock the cpu pins in place and protect them when sanding the heat spreader on the processor.

Hey Capper, I see you have your AMD system up and running! So how do you like AMD as compared to the Intel 3.2EE you had before? I noticed that under FSB on the tech sheets for Athelon 64's it says integrated does that mean you can't overclock a 64? I also finally got my 3200XL replacements in from Corsair 2-2-2-5 rocks. I don't have my dream system but I am getting there slowly. From where I am sitting Capper has the ultimate.

yeah, its very sweet. After having an AMD, I'll probably never go back to Intel. At stock speeds this 3800+ smokes my P$ at 3.71. the only thing that sucks are the multis are locked on the non-FX chips (I can reduce the multi, but can't go over 12X).
Overall this system is rock solid and I really like the Corsair LL at 2-2-2-5.

so up your HT/FSB and lower your multi. its the same process as an old barton but no higher multi.

which wouldn't make sense to me. i don't see a performance bump out of doing that, then by lowering the multi and raising the FSB, i have to loosen the timings.
To be perfectly honest, the performance i'm getting at 12X, 2-2-2-5, 210FSB are quite a bit better than i was getting at 3.71-3.75 on my P4.
For high performance testing, i'll push the envelope on the P4, but not my new baby.