9900KF 5.4, lapped die, direct die, no avx offset, no hyperthreading, evga 390 dark

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Apr 22, 2011
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Thought to share since this is hard forum. Haven't ran it longer than just over 5min, don't know if I will cause not a realistic use case for me. Pain in the rear to lap a die, my first time, took .3mm off the top. Not a pro here by any means, just an enthusiast having fun. Scores 1612 on C15, single core was 229.

5.4 Direct Die to Lapped Die .3mm off.jpg
451760_Cinebench_at_5.4-1.jpg
 
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Why lap a die?? The silicone is normally pretty dang flat and smooth.

(This is from someone who shot water under the ihs over the die to cool the chip)

I'm genuinely curious
 
Why lap a die?? The silicone is normally pretty dang flat and smooth.

(This is from someone who shot water under the ihs over the die to cool the chip)

I'm genuinely curious

Better temps. It allowed for a stable 5.4ghz overclock with an ambiant water loop. Previously temps were 70's, now usually 50's, a big difference when it comes to overclocking.

Main purpose is not to make it flatter, though you wanna keep it flat, it's to remove excess silicon material and significantly increase thermal conductivity from the top of the die to the waterblock in this case.

Never heard of direct water cooling a die but I'd like to hear more, how did it turn out, seems like a great way to directly water cool a die, I think you're onto something.

We need a direct die water cooling block, maybe just insert the chip and it has a gasket to seal as the water runs directly over the die, just seal the small leads on top of the chip with liquid tape.
 
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Better temps. It allowed for a stable 5.4ghz overclock with an ambiant water loop. Previously temps were 70's, now usually 50's, a big difference when it comes to overclocking.

Main purpose is not to make it flatter, though you wanna keep it flat, it's to remove excess silicon material and significantly increase thermal conductivity from the top of the die to the waterblock in this case.

Never heard of direct water cooling a die but I'd like to hear more, how did it turn out, seems like a great way to directly water cool a die, I think you're onto something.

We need a direct die water cooling block, maybe just insert the chip and it has a gasket to seal as the water runs directly over the die, just seal the small leads on top of the chip with liquid tape.
You got a 20C drop in temps from lapping the die?
 
Yeah I can see the delid doing some serious temp drops, but never heard of 10+ C drop from lapping the die.

Surprisingly there was a greater reduction from lapping .3mm of material off the die, go-figure.

Keep in mind most (including derbauer) only take .2 off, this one went beyond, not many willing to be this [H]ard;)
 
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Surprisingly there was a greater reduction from lapping .3mm of material off the die, go-figure.

Keep in mind most (including derbauer) only take .2 off, this one went beyond, not many willing to be this [H]ard;)
Having a hard time believing this. .1mm gets you 10C+ lower temps?
 
I tried to find out the thermal conductivity of silicon, and I got a lot of different answers, but it seems like 100-150 w/mk is a reasonable estimate. That's not super low, but given how small the die is relative to the amount of heat dissipated, I can see how a 0.3mm thick layer of excess silicon could hold back a lot of heat. It probably wouldn't make nearly as much of a difference on an older CPU.
 
Just to follow up, I did a little more digging, and the material we are talking about removing is probably magnesium silicon nitride, which conducts much worse than straight silicon. The thermal conductivity of standard MgSiN2 is only 25 w/mk, but there are new manufacturing techniques that can increase this 4-fold, and there are other materials such as β-Si3N4 that can be used in it's place that have conductivity as high as 110w/mk. If Intel is still using the regular stuff, and something tells me they probably are, then I can see this being a very beneficial thing to do.

I sort of want to try this on my delidded 4690K for fun/practice, but it's probably not worth it for that chip. Even though delidding dropped the temps by 15 degrees, it barely improved OC headroom at all (0.02V at the same speed). The same goes for my G3258. I guess if you're running into a thermal wall, it's worth it.
 
making me wish is didnt sell my 9900KS delided / LM that cpu had she strongest imc iv seen it ran 4400mhz cl 18 ram without a issue. might have been the last good intel cpu i could say i actually loved. but now i got a 5950x and soon the refresh with vcahce. good to hear this beast is still killin it.
 
One noob question thought, why lapping a die gives a better result ? It's a leftover of the silicon vaporizing process that "TETRIS" the particles one layer at a time ?

Or more of an armor to protect the die ?

Seems like Intel is a bit lazy if this could gives better results.
 
One noob question thought, why lapping a die gives a better result ? It's a leftover of the silicon vaporizing process that "TETRIS" the particles one layer at a time ?

Or more of an armor to protect the die ?

Seems like Intel is a bit lazy if this could gives better results.
it thins the top layer of the die so there isnt as much material to transfer heat through.
maybe
no
 
I might have you do the same to my 9600KF. I've been throwing caution to the wind because at the start of next month I will be upgrading to a 9900K/KS/KF. So perhaps I will take it on a suicide run before I swap CPUs out with a delid and lapped die, although I have heard the 9th gen chips are slightly better than 8th gen in terms of dissipating heat from the core to the cooling system. But very impressive results! My chip is good benching to around that frequency or slightly under that. Some of the more aggressive benches I have to turn it down to 5300MHz. But she sure does fly pretty high in this cold weather ;)

https://valid.x86.fr/0tg2ma

1640257881942.png
 
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