Lapped: same temperature - WHY???

[brucehao]

I find myself rather annoyed after spending an hour and a half sanding my cpu, only to find that temperatures remain unchanged.

Initially, my MBM would indicate that my P4 was 40*C/50*C idle/load.

Immediately after lapping it, MBM indicates 42*C/52*C idle/load. Now I'm assuming that after the ASIII cures, temperatures will drop back to 40*C/50*C as that was the case when I first installed the cpu.

Here's how I lapped it. I started with wet 600 grit and worked the cpu in little circles until only copper was visible. Then I did the same with 1000 grit and 2000 grit. I then applied a very, very thin layer of ASIII.

So, either I lapped the cpu incorrectly or applied too little ASIII - I could still see a tiny bit of copper through the ASIII.

Any input would be greatly appreciated.

Thanks in advance.

Yours truly, tired and irritated,

Bruce

 

[amdskip]

It is possible that the heatsink was fine to begin with. Give it a little time too and see what happens.

 

[brucehao]

Oh... sorry, I forgot to mention that I lapped the heat spreader on the CPU. It was not perfectly flat, as the copper beneath began showing up on the edges first.

I reapplied the ASIII and will wait and see what happens.

Thanks for the reply. Do you have any other ideas?

 

[SWScorch]

I find that lapping is highly overrated. thermal grease fills up the spaces between the to surfaces pretty well, so it really doesn't matter if they surfaces are "smooth" or "really really smooth." I think the real reason people lap is not so much to make the base of the heatsink any smoother, but to sand down the base if it's angled, thus resulting in better contact between the two surfaces.

Chances are your heatsink didn't even need to be lapped. And, it is possible to over-lap a heatsink, wherein it becomes too smooth and heat transfer actually decreases.

 

[Ketchup]

Originally posted by: SWScorch
I find that lapping is highly overrated. thermal grease fills up the spaces between the to surfaces pretty well, so it really doesn't matter if they surfaces are "smooth" or "really really smooth." I think the real reason people lap is not so much to make the base of the heatsink any smoother, but to sand down the base if it's angled, thus resulting in better contact between the two surfaces.

Chances are your heatsink didn't even need to be lapped. And, it is possible to over-lap a heatsink, wherein it becomes too smooth and heat transfer actually decreases.

Why can't people actually read what people post before giving advice? I am not blasting you personally, but brucehao has said twice that he lapped the CPU, not the heatsink, and he is still getting replies assuming he has lapped the heatsink.

Anyway, I am surprised your temps didn't go down, even a little. Did you lap the heatsink too, or just the CPU? Might wanna lap them both since you are in the lapping mood. What heatsink are you using?

From what I have read, lapping the heatspreader should be lowering your temps, so I think something has definately gone awry in your case.

 

[brucehao]

Thanks for the replies... I only lapped the cpu because the heatsink is pretty much brand new. I'm using a SLK-900.

Well, temperatures seem to have returned to what they were initially.

Hopefully they'll drop further as the ASIII cures.

 

[Ketchup]

Yes, from the reviews I have seen, the heatsink looks to have a mirror finish from the factory. How do you like the heatsink? Did you have another heatsink in that system you can compare it with?

 

[EdipisReks]

i got a 3 or 4 degree drop at load when i lapped my heatspreder. it was terribly uneven. i then got an even larger decrease when i removed the heatspreader: the die wasn't making very good contact.

 

[Baileybbk]

You want the heatsink to be FLAT not neccessarily ultra smooth. You will find that sanding with something more then 600 will usually DECREASE performance when using a thermal compound. (I think this was recently documented somewhere, sorry don't have a link handy.)

You need the spaces for the thermal compound to actually get out of the way........otherwise you are actually insulating the contact points with the thermal compound...think about 'hydroplaning'.

 

[SWScorch]

Originally posted by: ketchup79


Why can't people actually read what people post before giving advice? I am not blasting you personally, but brucehao has said twice that he lapped the CPU, not the heatsink, and he is still getting replies assuming he has lapped the heatsink.

Anyway, I am surprised your temps didn't go down, even a little. Did you lap the heatsink too, or just the CPU? Might wanna lap them both since you are in the lapping mood. What heatsink are you using?

From what I have read, lapping the heatspreader should be lowering your temps, so I think something has definately gone awry in your case.

I did read his post, and realized he lapped his CPU. The principle still applies however. I know I specifically mentioned only the heatsink in my post, because I am just so used to saying it that I guess it came automatically, but it goes for either surface.

 

[brucehao]

Hmm... maybe I sanded it with too fine a grit. I remember reading a few tutorials, though, which advised the use of at least 2000 grit sandpaper.

I used to have a Thermaltake Volcano 7+, and now I'm using the slk-900 with a Panaflow 9H1A. Temperatures dropped around 4-5*C during idle and 7-8*C during load.

Removing the heatspreader sounds tempting, but is a little too risky for my tastes. Hope I can stray away from that temptation 🙂

Yeah... I guess I'm just going to settle for these temps, which aren't bad to begin with. No water cooling and no phasechange, so I guess that's it. Unless someone has some bright ideas? 😉

 

[Ketchup]

Originally posted by: SWScorch

Originally posted by: ketchup79


Why can't people actually read what people post before giving advice? I am not blasting you personally, but brucehao has said twice that he lapped the CPU, not the heatsink, and he is still getting replies assuming he has lapped the heatsink.

Anyway, I am surprised your temps didn't go down, even a little. Did you lap the heatsink too, or just the CPU? Might wanna lap them both since you are in the lapping mood. What heatsink are you using?

From what I have read, lapping the heatspreader should be lowering your temps, so I think something has definately gone awry in your case.

I did read his post, and realized he lapped his CPU. The principle still applies however. I know I specifically mentioned only the heatsink in my post, because I am just so used to saying it that I guess it came automatically, but it goes for either surface.

Yeah, I remember the first article I read about lapping a CPU, I thought is was a typo! 🙂

 

[Ketchup]

Originally posted by: brucehao
Hmm... maybe I sanded it with too fine a grit. I remember reading a few tutorials, though, which advised the use of at least 2000 grit sandpaper.

I used to have a Thermaltake Volcano 7+, and now I'm using the slk-900 with a Panaflow 9H1A. Temperatures dropped around 4-5*C during idle and 7-8*C during load.

Removing the heatspreader sounds tempting, but is a little too risky for my tastes. Hope I can stray away from that temptation 🙂

Yeah... I guess I'm just going to settle for these temps, which aren't bad to begin with. No water cooling and no phasechange, so I guess that's it. Unless someone has some bright ideas? 😉

Not necessarily, I would try getting the thermal interface as thin as possible on the cpu, and don't put any on the heatsink before you install it, that might help; The reason for Artic Silver is to bridge the gaps between two non-flat surfaces, but since you CPU and Heatsink are smooth, there are no gaps that need to be bridged, so the Artic Silver may actually be insulating your CPU.