Thermalright Does NOT Recommend Lapping the Thermalright Ultra-120 Extreme

[Gregz]

From Thermalright's website:

Question 5: The bottom of the Ultra-120 eXtreme isn’t very shiny. Would I get better results if I lapped it?

Answer: A shiny surface does not necessarily mean a flat surface. Lapping only eliminates some of the larger gaps between the grains. We have demanding criteria for high quality especially when it comes to our heatsink base. The Thermalright heatsink you purchased does have a relatively flat surface therefore we do not recommend risking damage to your heatsink or your CPU DIE by lapping because results may not always be positive.

It seems that most people here believe that lapping improves temps, especially load temps. For instance, lot of posters in this thread (http://www.ocforums.com/showthread.php?t=517514&highlight=lapping) claim to benefit from lapping to the tune of around 1C-2C idle and 3-5C load. The problem is, those are the exact same results one should observe after the AS5 curing process has completed.

From the Arctic Silver website:

On systems measuring actual internal core temperatures via the CPU's internal diode, the measured temperature will often drop 2C to 5C over this "break-in" period.

So my question is, how do you guys know you're not just seeing the AS5 kick in, as opposed to getting better temps from lapping?

 

[MasterTelia]

cause they tried the HS before they lapped it

EDIT: and not everyone uses AS5

 

[sunrunner20]

Some of the people I have seen post laping results have enough experiance to remove the AS5 curing from the equation. Either by waiting to wait for it to break in, or not giving it a chance too.

 

[Hipcrostino]

A Manufacture would NEVER recommend lapping thier product to you. Infact they are very much inclind to do what you have found, and talk against it. this is clear because lapping your heatsink voids your warrenty. They also don't want a reputation that users must sand the base of thier products flat to get good performace. I don't understand how it comes as a supprise to you, or any others. They are protecting thier product image.

That said, lapping greatly increases performance when the base of your heatsink is not flat. Shiny has nothing to do with flat. Some people polish the bases, but IMO that is just another layer of stuff to get in the way of heat transfer, and its been proved not to help any further. Lapping is all about getting a flat base, i have seen 10c temperature improvements by lapping my old Thermaltake Big Typhoon because the base was shocking.

 

[theELVISCERATOR]

I wondered though if tiny wavy lines and valleys in the base would not increase total surface area of contact assuming paste is forced into these valleys....

 

[Anubis_386]

Exactly what Hipcrostino said .. a company would never tell its customers to mod their products for better performance ...

I was going to mod my U-120Ex, bought the paper .. but could never be bothered .. that said I will probs do it for my new quad (when they finally come out) ..

 

[jmsanders2]

Doesn't this fit the same catagory as companies recommending not to overclock? Who knows best, us or the company's PR department? I take full responsibility for my actions trusting in my knowledge and judgment.

 

[zexmarquies01]

Doesn't this fit the same catagory as companies recommending not to overclock? Who knows best, us or the company's PR department? I take full responsibility for my actions trusting in my knowledge and judgment.

You just said it best.

Companies what people to think that their products are great, and perfect right out of the box. they don't want customers to know that their processes are flawed.

I'v seen 5c temp difference from lapping the base of heatsinks in the past as well. I'v also seen how high your temps can get if your base was lapped wrong, and you have a very un-flat surface.

But all in all, you can't really blame them for stating this. Its in a company's best interest to make their products appear perfect. They don't have a Public Relations devision to tell people whats wrong, only to tell the people whats right.

 

[sunrunner20]

I wondered though if tiny wavy lines and valleys in the base would not increase total surface area of contact assuming paste is forced into these valleys....

That would be true if the thermal paste were a cooling method. However, it is not. The purpose of the paste is to aid the heat transfer from the cpu to the HS(or waterblock)

The issue is that no matter what paste you use it will have a significantly lower thermal transfer coefficent than perfect contact between the metals.

Thus, the perfect lap job would allow for there to be 0.0nm gap between the metals at every point of contact allowing the use of zero thermal paste at all.


I hope this makes sense.