Lapping processor and heatsink

[Wingo]

I've paid a lot of money for my system, so needless to say I want to squeeze every drop out of it. I've been looking at the bottom of my TRUE 120 heat sink and the heat spreader of my CPU and noticed that both have bumps/ridges all over them. The heatsink is by far the worse. The ridges are pronounced enough that when I drag my finger nail across it I sound like a miny wash board player. I've looked into the benefits of lapping and I am confident enough to give it a go. Seeing how my motherboard is RMAed at the moment, I need a project to fill in my time. I've read through this article: http://metku.net/index.html?path=mods/lapping/index_eng and it does seem to be a simple enough process for the CPU, but I'm thinking the heatsink might be a bit more difficult due to the bulk and weight. Any tips on how to make it an easy process, also any other information I should know before starting my handy project?

[NickN]

The processor is easy and you do not need to take it to a mirror finish.. thats just for show

It just needs to be flat and do be careful how far you go in sanding large amounts of material off. It only needs to be flat and any very deep grain lines removed.

As for the HSF.. that one is a bugger and I have done it twice with the TR120EX.. the third one I just had a friend do at a machine shop with strong warnings about how much to remove... enough was enough

[Wingo]

So taking it to a mirror finish doesn't give it that much more of an advantage? What grit of sand paper would you suggest taking it down to?

[NickN]

So taking it to a mirror finish doesn't give it that much more of an advantage? What grit of sand paper would you suggest taking it down to?

no.. thats just what the hardware sites do to look impressive

Mirror finish you are getting into theoreticals, trust me..

In reality the more 'cap' you sand off the processor and get it closer to the cores under that cap the better heat transfer and that can be dangerous because the i7 is not made like the old Q's

the goal is to bring both surfaces down to copper and get them to make as much contact as possible flat face to flat face.

I would say start with automotive 280 (or somewhere in there) and work your way up .. 400 then 600 is just fine.. you can go to 800 if you want to


The processor I normally do dry.. the HS I use a bit of water to help slide the unit easier but I dry sand the initial to get the major off of it first, then add water to the 280 and work up

Alcohol is used to clean everything up

sometimes I may add a touch of water to 600 to finish off the processor but do take care as that moisture can get up under the cap if you are not careful, use very little.


here is a real engineer showing the process on the CPU

http://www.thetechrepository.com/showthread.php?t=71

[Plugpennyshadow]

This was a thread I could use...At the right time to!  Thanks Nick for the run down...Printed and filed in the tweaking and clocking folder...

[Wingo]

Thanks for the info NickN. Is there anything that you don't know about computers? I swear your brain must weigh twice as much as a normal one with all the information in it. I'm going to lap my HS first and leave my CPU as I want to make sure my CPU still works when I finally get my motherboard back, just in case it needs to be RMA'ed. (I never determined which was the true cause of the fault, the problems pointed to the motherboard but I can't say for sure).

I have a few more questions to ask, if you don't mind answering them. Why did you need to lap the 120 more than once? Was it to clean it before reapplying a new lot of paste?

When you say the i7s aren't designed like the Qs, what do you mean exactly? Do they need a bit of heat to run well?

Last question is to do with thermal goops. Does the actual goop you use really matter that much, or is it more in the way it is applied? I was reading this article which is a bit dated but seems to prove a point: http://www.dansdata.com/goop.htm It shows that the cheap compunds can work as well as the Arctic Silver 3 as long as they are applied as well as the AS3 and stresses that the goop isn't there to actually conduct the heat as much as fill the gaps and leave as much metal to metal contact as possible. There are better conducters of heat than the goops, but the goops are designed to last as well as fill the gaps whie other materials will conduct the heat but not fill the gaps for a prolonged period of time. So in other words metal to metal is preferred over goops, goops are a compromise between conduction and longevity and are preferred over air pockets.

[NickN]

confusion.. I meant I have 3 120 units.. not that I lapped 1 unit 3 times


Thermal paste does make a difference (its NOT 10c though.. none of them do that!) if it is applied correctly (very thin) and if it is the right compound for the proc in use. I use OCZ Freeze as AS breaks down over a period of about 6 months and must be reapplied

There is a difference and the post you showed is VERY old.. back then AS was a joke but their newer formulas did improve things. For quads I switched from their AS product to their Ceramique which is less heat conductive but does not break down... I have not used any of their products in some months now.

[pengyman89]

when I lapped my e8400 and hr-01+ i did the processor dry in figure 8 patterns.

with the heatsink I put water and dish soap onto the sandpaper. this keeps the HS from stuttering as you pull it across but it still sands well enough. It all does take time though, i spread it across 3 days, doing little bits here and there.

also, with the processor, at even intervals you should rotate it 90 degrees to make sure you are getting everything the same.

all in all i was able to shave 2-3 degrees (celcius) off my idle temperatures and 10 degrees off load; well worth it.