lapping my northbridge heatsink

[stringcheeseincident]

i had these 2 scratches on the bottom of my northbridge heatsink, i needed to get rid of them so i decided to lap it. i got wet/dry sandpaper in 600, 1000, and 2000 grit. i was able to get most of the scratches gone, but i'm really only seeing progress on the edge. as you can see in the picture below, the heatsink was originally gold, but around the edges i'm getting to the silver. do i just need to spend more time doing this to get the bottom silver and to get the scratches out? do i need a more coarse grit sandpaper to use?

(i know i'm not done yet, i'm pretty much just wondering if sanding more will get the bottom even. i'm not gonna stop sanding until the scratches are completely gone.)

 

[zer0signal667]

Spend more time, mine was the same way. That's due to thermal contractions because of how the heatsink is processed, I would guess. So the base is pretty concave. Keep at it with lower grit sandpaper, and you'll get it flat eventually.

 

[rogue_jedi]

it also does that because when you move the heatsink, you usually tip it the slightest bit (or the sandpaper bunches up under the front edge) and it is enough to make a difference. so take your time to minimize the effect. also, i have found that holding the heatsink at a 45 degree angle makes it easier to not tip it. just as a general thing. also, rotate 90 degrees every five minutes or so. it helps.

but yeah, the heatsink is probably not flat either. you can check by placing it over a straightedge and seeing if the whole base makes contact.

good luck.

o yeah, i sometimes watch a movie while i'm lapping. just so it isn't as boring

 

[stringcheeseincident]

thanks, i'll keep working on it

 

[OPUS1]

Get ye some 200 paper , use it till it is flat then move upward. Not that much of a differance between 1000 and 2000 to warrant the extra effort though.

 

[mpK1337]

Why lap it when you can just slab some Artic Silver in there and be done with it?

 

[zer0signal667]

Why lap it when you can just slab some Artic Silver in there and be done with it?

Because you can lap it, slap some Arctic Silver in there, and be done with better results. Arctic Silver is meant to be a microscopic gap filler, but the void in there is far from microscopic.

 

[diredesire]

I'd go as low as 220 wet/dry sandpaper. It'll get the thing flat quick. 400/600 next, and then flip over the paper for that mirror shine (the back of wet/dry is typically up there.. i've heard up to 10k grit)! One of the best tips i've ever heard on this forum...

but in the end, it might all be a waste, chances are your northbridge isn't flat either ;D (unless you're using an IC7 variant... then it wouldn't matter)

 

[_Korruption_]

but in the end, it might all be a waste, chances are your northbridge isn't flat either ;D (unless you're using an IC7 variant... then it wouldn't matter)

The northbridge on my A7N8X is far from flat.

 

[RickyJ]

There was a guide floating around that showed how to lap the northbridge too.
Use a straightedge (ie: metal ruler) and run it across the NB, looking for gaps. If you can't see between the chip and ruler, it's flat enough.

 

[diredesire]

The northbridge on my A7N8X is far from flat.

yeah, i hear ya. i own one... and my epox 8rda+ isn't so flat either.. most of my nforce 2 boards aren't flat... but it'd be ok if the center was raised, but in my experience, the center of the NB is actually concave

 

[RickyJ]

yeah, i hear ya. i own one... and my epox 8rda+ isn't so flat either.. most of my nforce 2 boards aren't flat... but it'd be ok if the center was raised, but in my experience, the center of the NB is actually concave

That tells me that there's room to lap the NB safely.

 

[diredesire]

That tells me that there's room to lap the NB safely.

Definitely. Attach a small piece of sandpaper to a small, flat surface and wet sand the board. I'd use some masking tape to tape off the surrounding aread before doing so, and you will see some pretty impressive gains. Most motherboard manufacturers get around this 'flaw' by using thick thermal pads, which are retardedly inefficient. Good luck with RMAing the board if you ever need to, though ;D

But then again, the [H] mentality isn't exactly beneficial for the pocketbook, eh?

 

[_Korruption_]

yeah, i hear ya. i own one... and my epox 8rda+ isn't so flat either.. most of my nforce 2 boards aren't flat... but it'd be ok if the center was raised, but in my experience, the center of the NB is actually concave

The heatsink image in the first post looks like a Zalman NB32J... I have a Zalman NB47J on my northbridge. If that yellow heatsink there is concave like that (assuming both heatsink models are produced on the same process), there must be a huge gap between my northbridge and heatsink.

 

[RickyJ]

Definitely. Attach a small piece of sandpaper to a small, flat surface and wet sand the board. I'd use some masking tape to tape off the surrounding aread before doing so, and you will see some pretty impressive gains. Most motherboard manufacturers get around this 'flaw' by using thick thermal pads, which are retardedly inefficient. Good luck with RMAing the board if you ever need to, though ;D

But then again, the [H] mentality isn't exactly beneficial for the pocketbook, eh?

It's not like S462 boards are that expensive nowadays anyway. My A7N8X-X drops well below $100 CDN on sale around here.

I'll test the contact patch between my NB and MCX159 when I get around to overhauling my PC. This will occur as soon as my reservoir stops giving me headaches...