I recently had OC'd my aging AMD Athlon 3700+ San Diego from 2.2gHz to 2.9gHz...all of this on stock cooling.  I was so thrilled!  Until that is, I started playing a semi-recent game.  See, I'm addicted to America's Army.  I don't know for a fact, but the game is so old I bet someone with an IGP could play it.  Needless to say, it does not tax my CPU or GPU in anyway.
 
So one evening, I decided to download the 7-day trial of Lord of the Rings Online.  After playing for about 15 minutes, I could hear through my headphones what sounded like an airplane in my office.  Sure enough it was my HSF running at close to 5000 RPM's and the CPU was hovering at 58C.  At first I thought “okay…well, I can deal with this.”  But on the second evening, I couldn’t anymore.  So I sent off to Newegg to send me a shiny new Xigmatek S1283 Rifle CPU Cooler, rated #1 by FrostyTech.  After 3 days, my shiny new CPU cooler arrived.  When I removed all the popcorn from the shipping box and pulled out the CPU cooler box, I saw the biggest fan I have ever seen (outside of your normal house fan).  My immediate reaction was…”NO WAY!  There is no way thing thing is fitting in my case!”
 
I tried eyeballing it best I could before I started taking apart the stock setup, but I just couldn’t be sure.  So I figured…what the hell…I’m going to just go for it and see what happens.  Worst case scenario, I get to apply AS5 to the stock setup rather than the icky thermal pad that it had been using.
 
It was about this time that I started debating lapping my CPU.  Not sure if I was ready for this big of an adventure I did some reading about the process and also checked on the cost of a replacement CPU in the event I destroyed this one.  Newegg had an AMD Athlon 4000+ for $40.00, so I didn’t feel there was much risk in giving this a go.
 
I ran down to my local OSH Hardware store, grabbed 3 sheets of 220 grit Wet or Dry Sandpaper, 2 sheets of 400 grit and 1 sheet of 600 grit.  The total cost was around $.98 per sheet, so 6 bucks out the door, roughly.  I brought all of this home and began preparing.
 
I had purchased the Arctic Silver thermal grease remover kit from Newegg when I bought my cooler for $5.00.  Most say that you can do it with alcohol or some other product found in your home, but I just wasn’t comfortable with that…so I forked over the $5.00 for something that is probably just a repackaged product found in my home at a higher cost, but it eased my mind.  
 
Removing the thermal material was very easy with this.  I just put a few drops on the CPU, used some q-tips to wipe it around and then wiped it clean with a paper towel.  Next, I did as many of the guides stated…I taped the 220 grit to a piece of glass and taped that down onto my table.  Then I grabbed my CPU and began sanding away.  After about 25 minutes, I wasn’t really seeing any results.  Just a small portion of the nickel had started to scrape away, but not enough in my mind for the amount of work I was doing.  Either way I kept at it.
 
After about an hour, and 1 ½ sheets of the 220 grit sandpaper, I started to really see the results.  What I found out was that the sandpaper wears down really easily, so I had to change fairly often to ensure that it was actually working.  Good thing I bought 3 sheets!
 
Finally…after about 1 hour and 45 minutes, I had removed all of the nickel plating on the CPU and had a nice semi-shiny copper surface.  So I moved up to the 400 grit paper.  I had drawn an X on the CPU to see if the surface was even or not.  As I would have imagined it was not.  The CPU was sorely concave (yes, concave…not convex).  The 400 grit sheets really seemed to event her out.  Lastly I moved to the 600 grit and ended up with a fairly flat surface that was relatively shiny.  
 
Other people on website opted to buy higher grits (1200, 1500 and so forth) to make a super clean shiny surface, but I’m of the mindset that I wasn’t going to see that surface anymore once the HSF is on it, so who cares how shiny it is.  Next came the scary part for me…actually putting on the new HSF.
 
This was my first time working with an aftermarket cooler…let alone a cooler of this gargantuan size!  I used about a pea sized drop of AS5 and spread it on the CPU with a business card which provided me with a very thin, but good covering (thanks PC Gamer for the tip!!!).  Since my motherboard is a socket 939, the installation of the heatsink was very, very easy.  Just hook up the retaining clips and lock it.  No screws, no push pins…it was a piece of cake.  It was so easy; I don’t understand why some people say that it’s easier to remove the motherboard.  I didn’t, but maybe it’s just easier for socket 939.  
 
Next I had to install the fan.  This is a little difficult because you have to get these rubber supports through these little holes on the fan itself which is used to support the fan on the heatsink.  After a little bit of finger muscle work, I had done it.  Actually getting the fan onto the heatsink was a breeze.
 
Finally, the moment of truth.  The Power-Up!
 
She booted right up.  I immediately went to check the fan speed and the temps.  What was amazing is that my BIOS was set to alarm me when my CPU fan speed drops below 1200.  Well this fan runs around that, but was keeping my temps at 32C.
 
Here are how my temps matched up:
 
Stock HSF @ 2.9gHz Overclock
Idle – 46C
Load – 58C
 
Xigmatek HSF @ 2.9gHz Overclock (lapped)
Idle – 32C
Load – 44C
 
What I find most amazing is that at full load the fan only runs at 1400 RPM’s and is dead silent.  I don’t doubt that a seasoned professional could have probably lapped the CPU better or hooked up the new HSF better than me, but being a first-timer, I am really proud of the fact that I did it and how it turned out.  The drop in temps absolutely astounds me!
 
I’m part of an America’s Army clan and after I was done last night I hopped on TeamSpeak with a bunch of them.  I think my results have prompted a few of them to want to jump in as well and try to do the same thing with their CPU’s, but they have newer setups (Core 2’s), so we will see.  Chickens!
 
This experience has taught me a terrific lesson.  It took about 3-3 ½ hours to complete the whole process, but it was worth it in every way.  I am now content to lap every CPU I ever get (after the warranty is up, of course) and I will always use an aftermarket HSF.  To me, the results don’t lie.  The numbers speak for themselves.  
 
I had a blast!  I took a ton of pictures of the process, but I haven’t yet had an opportunity to pull them off of my camera.  And now I do not have a jet engine in my office driving me nuts!

Good job. .  
 
Side note: Try some shaving cream instead of water. Trust me that stuff works. I get a shinier smoother surface with shaving cream than water. I know it sounds weird but it works for me.

May favourite after  some experimentation is neat washing up liquid (I kid you not!!) The detergent binds up the metal particles very and they can be throughly rinsed off under the tap. They can be reused when dry and still work fairly well (the particles clog up the abrasive particles on the sand-paper).

Why stop at 600 gritt... Personally I go up to 2,500!! I have got into hardcore lapping (i.e. GPU and chipset blocks as well!!)

Older socket 939/940 Athlon-64/Opteron processors have all got dreadful heat-spreaders from my experience... You are right they are all deep concave!! My old Prescott socket 478 wasn't quite so bad. However a newer E2180 was much lighter and actually needed to be weighted down for lapping!! It was also much flatter to start with (smaller surface area??)

I recently helped my flatmate build up a socket 939 Opteron 165 system. I lapped the CPU and stock heatsink to 2000 gritt. Overclocked to 2.8Ghz with both cores max'd using 2xCPUburn processes we were looking at a core temp. of <40C load!! I was blown away. However the lapped E2180 OC and running at 3.0Ghz and 26C idle was a revelation!! The load temps. were also <40C. Thats with a lapped Cooler Master Hyper TX Socket 775 CPU Cooler BTW. (Rubbish cooler as the fan is way nosier than a Arctic cooling fan). This cooler was biatch to lap as well (tall heatpipe cooler type)...

I am totally sold on lapping. However I found it difficult when I start 2 years ago as I was trying to lap with wet sandpaper. This is much harder... My results looked s*** (a very fuzzy mirror)!!

Bob

Yeah, all of the guides I have read said to use some sort of lubricant, such as soapy water on the sandpaper to help the CPU glide.  I personally found this to make my work harder.  It seemed, to me anyways, that when I wet the sandpaper it didn't really do the job of peeling away the nickel plating.  So after the first damp sheet of 220 grit, I stopped wetting the sandpaper and went the dry method the rest of the way.
 
I wanted to lap the HSF as well, but if any of you have had a chance to see the Xigmatek HSF, it is really three heat pipes and not a flush surface.  I wasn't really sure what to do, so I left it alone.  Maybe next time.  I've heard of a burn-in effect when using AS5 where the temperatures actually get better over a period of time.  I'm already witnessing this effect.  Last night my load temps were up to 46C, but after 12+ hours of stress testing, I now can't break 44C which leads me to believe that there really is a burn-in effect.  I'm going to stress test for about 24 hours over the weekend while I'm out of town and maybe I'll see an even better reduction in temps when I'm through with that!  
 
You know...one thought I was having today is this...how do I know if I put the fan on backwards or not?  It didn't exactly say "Front" or "Back" anywhere.  It just got me wondering...what if it's backwards...how much further down would my temps come?   I'm going to have to look when I get home.

^To see the direction of the fan fell what way is most of the air moving. Generally (98% of the time) the air will move the way fan is facing.

Yeah, I have seen/heard a few of my friends do this. But I prefer Acetone and Tech grade Alcohol.

Washing up liquid?  Like Dawn or Dial liquid soap?  Or laundry detergent?  That is one hell of an experiment!

^Yup. I need to try that too.

Update:
 
My PC sits in an enclosure that is part of my desk.  I decided to take the PC out of the enclosure and monitor the temps.  I was amazed!
 
Idle - 31C  
Load - 39C
 
Not a major reduction from the idle temperatures, but the load temperature dropped another 5C.  I'm not shocked, but just truly amazed at how cool this PC is running now.  That almost 20C lower under load.  This cooler rocks!
 
P.S. I do have the fan on right...!

 
Like one large drop of concentrated liquid for handwashing dishes (you got that kinda stuff in the USA?) I was using Co-operative own-brand washing up liquid (from the UK)!! Not a value-brand (too much water)!!
 
You really don't want to sand dry. Sure it works well but after a few projects you will start to develop metal poisoning and/or emphysema !!    
 
My method is one of the best as the detergent locks up the metal particales and you can easily rinse them away to reuse the sandpaper. Neat washing up liquid is also a good lubicant and makes the sanding quite effortless. The key is to only use a small drop each time and always apply it to dry sandpaper.
 
Surely an alcohol & Acetone mixture is not as good a lubricant - certainly not quite so innocuous to human health as washing up liquid when inhaled??!!  
 
Quoting from http://www.frostytech.com/articlev [...] cleID=2233:

 
Yeh I have seen that Heatsink before... It would be quite hard to lap it but I guess not impossible...?? Sounds like it is very flat anyway from the review. You would need to use a small bit of perspex with sandpaper attached and fix the HSF in place with a clamp.
 
Good load temps - but you can do better if you went up to 1200+ gritt you get a real mirror surface - that will buy you temps below 40C load!! I buy the wet-dry paper in bulk on-line now...    
 
Bob
 
 

How do you guys lap chipsets?

 
If you mean my previous post where I muttered about lapping chipsets I meant a waterblock... Its for the ol' Intel i875P chipset which is a naked IC package, with no heatspreader, so I am not going to do anything with that!!
 
Even if a chipset has a heatspreader - anything soldered to the motherboard is going to be a biatch to lap as I far as I can see. Once you've knocked a few capacitors off it might be time to give up!!
 
Bob

I thought about lapping my GPU, but after reading a guide on how to do, I don't think I'm going to jump into those waters.  That looked to complicated for me.  
 
I'm in love with what I have though...can't wait to lap a new 9850BE!

 
Yeh don't... The core chips typically don't have heatspreaders from my experience!! It's also hard to get to them as they typically soldered into the PCB...
 
Bob