CPU Lapping

[furnace]

I've discovered that my E6300 is concave! So I guess I need to lap it. I have a few questions about it, for anyone who has experience with lapping.. If you can advise me with any of this then please do

Right, this is a paint drawing of my problem

The gap, in reality, is really small. But I guess it's enough to make a big difference - my heatsink's base is at least 15'c cooler than the core temp - sometimes even 25'c cooler, so this would explain why! I would only expect a 5'c, MAYBE 10'c, difference between the core and the heatsink.

Would you agree that this is my problem? I idle at 57'c where others are idling at 35'c on the same processor.

Can you give me advice on lapping?

Is it worth lapping and voiding the warranty?

From what I've read, you get a little bit of oil and drop it onto each piece of sandpaper you use. First, you use 400 grain, then 800 grain, then 1500 grain, then 2000 grain. When doing it, you put the processor IHS-down onto the sandpaper, which should be on a pane of glass. Then you move the processor in small circles applying gentle force.

How long should I do it on each size grain sandpaper? I guess longer with the 2000 than the 400?

Thanks for any advice or warnings

 

[furnace]

At the moment I'm getting 48'c idle @ 2.1Ghz on an E6300, and 65'c full load A 15'c drop would be VERY appreciated! *crosses fingers*

I've emailed intel about it (quoting stock speed temps though, which are 46'c->57'c) and I'll see if they reply with anything worthwhile. E.g. the offer of a replacement.

But, tbh, tomorrow I think I will be lapping the processor.

Can you get those sandpaper's from B&Q and any other hardware store?

Also, you do it with the processor face-down on sandpaper... how do you move the processor around whilst keeping a bit of force on it without touching the pins?

Cheers

Are you sure it's not your heatsink that's out of shape? Just making sure.

Yeah, before hand I checked the heatsink with the edge of a metal ruler and bright light and it was fine. Then I checked the processor with the edge of the metal ruler and noticed it, then used the heatsink just to confirm they weren't properly contacting each other (wudda been great if the heatsink was convex and the processor concave, eh! lol).

just out of interest, how can you tell its concave?

Concave, is like a flat surface with a dip in it. Convex is the opposite, so it'd be a flat surface with a bump on it. If it were convex, I would be able to make the two wobble against each other slightly

 

[furnace]

Just hold it by the edge, 775 chips don't have pins on the chip.

I bought mine from a model shop, but it seems that your local autoparts store might have the right grits. As far as I can tell B&Q don't have that fine a paper.

Jokester

Chips, blobs, whatever... hehe

Thanks for the advice, I will pop into B&Q tomorrow to get what I can, then I'll go to the model shop and see if they have what I need.

If you think of anything else I should know please tell me - this feels quite a daunting task and don't wanna go wrong anywhere!

Halfords might ..? What would you want paper that fine for on a car? Smoothing surfaces for painting? (just so I know whereabouts to look in store)

 

[furnace]

Have a look in here on how to test how flat it is.

Jokester

Using that, my heatsink seems pretty flat - although I can't see how I'd lap it without taking the "legs" off it. Either that or I'd need a pretty small pane of glass. But yeah, hopefully that won't really need lapping just cleaning up a bit.

The CPU, I used the optical thingymajig and the very corners of the IHS make the lines wobble, so I guess that's the raised edges doing that..!

Well I'm gonna go pop out to halfords and see what they got in a second (edit: wtf, i swear halfords shut at 8... that was a waste of petrol). I might do it tonight as i'm pretty awake and have nothing better to do.

Although I've emailed intel about it, maybe I should wait for their reply? But tbh as it's under 65'c at stock speeds they'll probably tell me it's fine

Another question; why should I make the paper wet? What difference does it make?

 

[furnace]

Been considering this myself as I'm running about 48C Idle and over 60C under load, tried reseating the (stock) cooler, but didn't help. I got an Arctic Freezer 7 Pro to fit, but am waiting for my DS3 mobo to arrive before I break that out of the box.
If I don't see a marked drop in temps then I may well try lapping the CPU, bit dubious about the process though, I'm especially concerned about water getting under the IHS and causing probs.

Yeah, water is a worry for me too. Just be careful you only get it on the paper and not enough of it to make any sort of splash. You don't wanna be getting it on the pins of the CPU either May also be worth lapping the Freezer 7 Pro as supposedly the finish on them isn't great..!

I'll let you know what my results are when I get the paper and have a go myself. The only thing I'm thinking it where am I going to get a flat pane of glass... I may dismantle a photo frame.

 

[furnace]

Well I got some 1500 grain paper, was the finest in halfords. There's 400 and 800 in the garage already. I'll give it a go in a bit

Has anyone had any horror stories regarding lapping? IMO there's not much that can go wrong unless you get the pins wet or touch them?

 

[furnace]

Would putting a bit of blue-tac or something over the air gap be a good idea or a stupid idea?

 

[furnace]

OK cool. Well off goes the computer, I'll let you know how long it took me to kill the processor

 

[furnace]

Well, it's all done... right down to the copper, 400, then 800, then 1500. Used a mirror to ensure a smooth surface. And the temps? Still high! 57'c full load and 45'c idle @ 2.1Ghz.

Hrm... What now?