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Is lapping your Heatsink and CPU recommended or merely an option?

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November 18, 2011 4:03:29 PM

Hey guys,

This would be specifically for an i5-2500K CPU and a ZALMAN CNPS9900MAX-B Heatsink in an Antec 300 (possibly 600) case with a GIGABYTE GA-Z68X-UD3H-B3 motherboard.

According to the guide at the top of this forum the lapper achieved ~7-10 degrees cooler results.

Are these results likely to be close using my listed components? If they are likely to be 7-10 degrees cooler, is it a big enough difference to be worth voiding the warranty (in your opinion, please don't say it's up to me...I want to know if you'd do it...it will still be up to me for the final decision)?

Any other factors that should be considered?

Thanks,
-TG
a c 120 à CPUs
a c 183 K Overclocking
November 18, 2011 7:22:06 PM

Lapping was a necessity a few years ago when coolers had poorly machined finishes..
I'm talking 775 socket era.
It's something i wouldn't bother with these days imo.
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a c 172 à CPUs
a c 197 K Overclocking
November 18, 2011 7:51:40 PM

Agree with davcon here. My TRUE (great cooler, poor machine work on the base, about 4 years old now) had a visible high spot just off center. I hand lapped down to 1500 grit to flatten the base.

Today, the finishing work is much better. If I ordered a cooler and received one with a sloppy finish, I'd RMA it.

Something to keep in mind - you can screw up and ruin the cooler.
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November 18, 2011 7:53:19 PM

I did remove the CPU and Heatsink from their packages and put a razor blade on them to see if I could see light through.

They both were not perfectly flat. I guess I could just mount them and see what temps I get, then decide if I need/want them to be lower.

How exactly would one screw up and ruin the cooler? If I did end up lapping, I'd like to know what not to do.
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a c 120 à CPUs
a c 183 K Overclocking
November 18, 2011 8:00:33 PM

Something to also keep in mind.
I know for a fact Thermalright currently machines their cooler bases(slightly convexed) like that on purpose.
Engineered for better temps according to what i've read.
Must be something to that since their coolers are among the very best.
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November 19, 2011 2:49:23 AM

davcon said:
Something to also keep in mind.
I know for a fact Thermalright currently machines their cooler bases(slightly convexed) like that on purpose.
Engineered for better temps according to what i've read.
Must be something to that since their coolers are among the very best.


That is interesting. How the heck do you guys learn all this?

Both the surfaces are very slightly convex (curving/bulging out) at certain points.

Davcon btw...if I have 1/2" from the case bottom tabs (Antec 300 or 600), should I face the PSU down?...If so, will there be enough cool air in the space between the PSU and case bottom, or should I cut in a hole (and put a filter) for intake?
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November 19, 2011 3:53:34 AM

TopGun said:
That is interesting. How the heck do you guys learn all this?

Both the surfaces are very slightly convex (curving/bulging out) at certain points.

Davcon btw...if I have 1/2" from the case bottom tabs (Antec 300 or 600), should I face the PSU down?...If so, will there be enough cool air in the space between the PSU and case bottom, or should I cut in a hole (and put a filter) for intake?


I def wouldn't mount the PSU that way unless it was vented. If vented then that is the preferred way to do it.

An article a few years back in CPU magazine was where I heard originally that Thermalright made their plates slightly convex as they found better cooling efficiency that way. Also heard this on Anandtech.
Of course now the most efficient coolers seems to have exposed heatpipes, and they typically are somewhat recessed to the base plate. So again machining is not such a big deal anymore. I also didn't lap my most recent HSF because of the exposed heat pipes. But I would again if I felt the need to.
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a c 120 à CPUs
a c 183 K Overclocking
November 20, 2011 5:14:06 AM

TopGun said:
That is interesting. How the heck do you guys learn all this?

Both the surfaces are very slightly convex (curving/bulging out) at certain points.

Davcon btw...if I have 1/2" from the case bottom tabs (Antec 300 or 600), should I face the PSU down?...If so, will there be enough cool air in the space between the PSU and case bottom, or should I cut in a hole (and put a filter) for intake?

Ya know what i installed my HX-750 fan down in my 902(no cut-out) over 2yrs ago.
I haven't had any issues but i have very good airflow.
Asked my buddy, the head-tech at a very good pc shop and he said no worries.(btw i'm a pc A+ tech too)
Mounted fan down in a few cases with the cut-out and i'm always cleaning the filters and the psu fan.
Experiment it might be just fine fan down.
I know mine is!i also periodically check it and it's clean as a whistle.
The one's with cut-outs = always clogged!
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November 20, 2011 5:46:34 AM

davcon said:
Ya know what i installed my HX-750 fan down in my 902(no cut-out) over 2yrs ago.
I haven't had any issues but i have very good airflow.
Asked my buddy, the head-tech at a very good pc shop and he said no worries.(btw i'm a pc A+ tech too)
Mounted fan down in a few cases with the cut-out and i'm always cleaning the filters and the psu fan.
Experiment it might be just fine fan down.
I know mine is!i also periodically check it and it's clean as a whistle.
The one's with cut-outs = always clogged!


Thats a good story Dav. It just goes to show that sometimes when it comes to airflow what can seem counter intuitive can work just dandy!
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November 20, 2011 7:20:12 AM

Topgun, if you think you can do a better job of 'finishing' the surface of a block of aluminum than the manufacturers who have millions invested in the process, go for it!
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a c 172 à CPUs
a c 197 K Overclocking
November 20, 2011 9:45:20 AM

TopGun said:

Davcon btw...if I have 1/2" from the case bottom tabs (Antec 300 or 600), should I face the PSU down?...If so, will there be enough cool air in the space between the PSU and case bottom, or should I cut in a hole (and put a filter) for intake?

I have three Antec 900 cases. All the power supplies are mounted with the fan facing up. All three house systems are running just short of the ragged edge of instability.

Even while stress testing (Prime95), the PSU exhaust has never been more than 5 C over ambient. And hard drive (drives in the lower bay) temps have never reached 30 C.

I cut extra holes in the motherboard tray for cable management:
http://www.tomshardware.com/forum/264112-28-antec
and I could have cut another hole into the bottom of the case, but after I built and test my first system, I decided it wasn't necessary.
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November 20, 2011 1:25:50 PM

davcon said:
Ya know what i installed my HX-750 fan down in my 902(no cut-out) over 2yrs ago.
I haven't had any issues but i have very good airflow.
Asked my buddy, the head-tech at a very good pc shop and he said no worries.(btw i'm a pc A+ tech too)
Mounted fan down in a few cases with the cut-out and i'm always cleaning the filters and the psu fan.
Experiment it might be just fine fan down.
I know mine is!i also periodically check it and it's clean as a whistle.
The one's with cut-outs = always clogged!


Ya, not cleaning as often sounds like a good reason to at least test out the no cut-out plan first. I can always change it up later if I'm not satisfied.

Do you periodically take your case apart then to check it or how do you go about this (seemingly pain in the @ss) process?

It doesn't make sense to me why (with a good filter) it would get more dust than with no cut-out...do you have any ideas why this might happen?
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November 20, 2011 1:30:40 PM

DelroyMonjo said:
Topgun, if you think you can do a better job of 'finishing' the surface of a block of aluminum than the manufacturers who have millions invested in the process, go for it!


I don't know if this is meant as encouragement or as a sarcastic put-down, but according to a lot of test results people have gotten very good results doing a "better" job of finishing.

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November 20, 2011 1:34:09 PM

jsc said:
I have three Antec 900 cases. All the power supplies are mounted with the fan facing up. All three house systems are running just short of the ragged edge of instability.

Even while stress testing (Prime95), the PSU exhaust has never been more than 5 C over ambient. And hard drive (drives in the lower bay) temps have never reached 30 C.

I cut extra holes in the motherboard tray for cable management:
http://www.tomshardware.com/forum/264112-28-antec
and I could have cut another hole into the bottom of the case, but after I built and test my first system, I decided it wasn't necessary.


Why would/did you mount face up? Were there not tabs to mount the PSUs on? If there were/are tabs like the 300/600 cases have, would/have you experimented with a face down setup to see if exhaust could get even cooler?
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a c 120 à CPUs
a c 183 K Overclocking
November 20, 2011 1:55:36 PM

TopGun said:
Ya, not cleaning as often sounds like a good reason to at least test out the no cut-out plan first. I can always change it up later if I'm not satisfied.

Do you periodically take your case apart then to check it or how do you go about this (seemingly pain in the @ss) process?

It doesn't make sense to me why (with a good filter) it would get more dust than with no cut-out...do you have any ideas why this might happen?

In my situation it's not too difficult i have semi-modular units in all my rigs.
I do a thorough clean twice a year,i'm a smoker.
I do clean all my filtered intakes on a regular basis though(once a month)
Btw all my units are also off the floor.
You'd think the units fan down with filters and cut-outs would be fine.
That's not the case though they're always clogged up.
I have to clean them at least once a month.
I vacuum once a week like most people.
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November 20, 2011 2:02:30 PM

davcon said:
Something to also keep in mind.
I know for a fact Thermalright currently machines their cooler bases(slightly convexed) like that on purpose.
Engineered for better temps according to what i've read.
Must be something to that since their coolers are among the very best.


Here is an article claiming the flatter the better...

http://www.overclockers.com/heatsink-mounting-pressure-...

Do you think you could please find/link the article you mentioned about engineering slightly convexed bases for better temps?
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a c 120 à CPUs
a c 183 K Overclocking
November 20, 2011 2:15:50 PM

TopGun said:
Here is an article claiming the flatter the better...

http://www.overclockers.com/heatsink-mounting-pressure-...

Do you think you could please find/link the article you mentioned about engineering slightly convexed bases for better temps?

Once again from a 775 platform = old tech and coolers had poor machining back then.
Many of the best modern coolers are crowned(convex) for point loading under compression = better performance.
Most good water blocks are also finished the same way.
http://www.overclockers.com/premium-heatsink-shootout/
If you can find an article on lapping for a modern platform i7 1366/1156/1155 knock yourself out.
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November 20, 2011 4:18:59 PM

Here is an article about why NOT to lap your CPU and Heatsink...not really sure if the guy is being serious or trying to be funny.

http://hallicino.hubpages.com/hub/How-to-destroy-your-C...

It probably doesn't make a lot of sense for me to risk trying lapping at this time.

1.) I don't plan to do a massive 24/7 OC at this time. I want to make sure this PC will run good for (hopefully) 3-5ish years. If I can somehow sell it, I would definitely build another ASAP...I believe I might have caught the building bug.

2.) The Sandy Bridge CPUs aren't supposed to run very hot in the first place...along with only doing a slight overclock, I think my case will have plenty of airflow.

3.) When the time comes to build a new one, the price to replace the CPU and Heatsink should be a little lower if something should happen to go wrong. I will definitely experiment at that point so I can know for myself for sure.

So, there's not really very much incentive (besides curiosity and perfectionist issues) to lap at this time. Not enough potential reward for the risk.

Also, I noticed that the edges of my CPU appear to be the higher areas...do you think maybe that's why Heatsink manufacturers have a convex middle area...so it can kind of fit into the slight IHS "indentation" better?
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