News Intel Core i9-14900KS runs at all-core 6 GHz with direct die cooling - with headroom to spare

[Admin]

Overclocker Der8auer showed off how his direct die CPU water block cooled the 14900KS to the point of hitting 6 GHz on all eight P-cores.

Intel Core i9-14900KS runs at all-core 6 GHz with direct die cooling - with headroom to spare : Read more

 

[bit_user]

I often wonder how much direct-die cooling would benefit normal air coolers.

On a related point, does anyone know if the efficiency of heat pipes drops, as you go past a certain number of Watts? Because that's about the only reason I can see why air coolers might not also benefit from this approach.

 

[taz-nz]

I often wonder how much direct-die cooling would benefit normal air coolers.

On a related point, does anyone know if the efficiency of heat pipes drops, as you go past a certain number of Watts? Because that's about the only reason I can see why air coolers might not also benefit from this approach.

With any modern heatpipe cooler, you need some form of heat spreader between the small CPU die and the heatpipes, otherwise only a couple of heatpipes would be in contract with the heat source and the rest would offer almost no cooling. There are some coolers that used a vapor chamber to spread heat evenly across heatpipes, but this gets complex and expensive to manufacture.

Yes you can stall a heatpipe if you exceed it's thermal capacity, but you have to force heat into the heatpipe faster than the rest of the heatsink can extract that heat from it for this to happen, so the CPU will normally thermal throttle long before this is possible.

But in extremely hot environments the heatsink can become so inefficient that whole heatsink becomes heat soaked and the body of the heatpipe raises to the point that all of it is above the boiling point of the working fluid, and the working fluid therefore stays in it's gaseous state, stalling the phase change heat cycle that make the heatpipe work, at this point the heatpipe is just a very inefficient shaped piece of copper.

 

[bit_user]

With any modern heatpipe cooler, you need some form of heat spreader between the small CPU die and the heatpipes, otherwise only a couple of heatpipes would be in contract with the heat source and the rest would offer almost no cooling.

Most air coolers do seem to have a base. I had bought into Cooler Master's "Direct Touch" pitch, but either they patented the heck out of it and refuse to license it to just about anyone else, or it's not such an advantage, even if you do have a heatspreader.

There are some coolers that used a vapor chamber to spread heat evenly across heatpipes,

Yes, and this is what high-end GPUs do. Also, server heatsinks.

the body of the heatpipe raises to the point that all of it is above the boiling point of the working fluid,

Yes, good point. I think/hope we're not talking about such an extreme situation.

Do you know what the boiling point typically is, for PC heatsink heat pipes? It seems like there should be a nonlinear bump in cooling efficiency, as you cross this threshold. If one did a careful test of power vs. temperature, there should be a distinct uptick, especially on coolers with just a couple heat pipes.

 

[taz-nz]

Most air coolers do seem to have a base. I had bought into Cooler Master's "Direct Touch" pitch, but either they patented the heck out of it and refuse to license it to just about anyone else, or it's not such an advantage, even if you do have a heatspreader.

The Coolermaster direct touch relies on the CPUs IHS to spread the heat across the heatpipes, but the IHS isn't the ideal thickness to spread the heat efficiently, so the direct touch heatsink preforms worse if mounted with the heatpipes mounted parallel with the die vs across the die. The uneven surface would destroy a CPU in direct die application.

Yes, and this is what high-end GPUs do. Also, server heatsinks.

Cooler master did it on their V8 series of desktop coolers, but they cost as much as a cheap 240 AIO, with worse performance. Vapor chambers are most commonly used where space and form factor matter more than cost.

Yes, good point. I think/hope we're not talking about such an extreme situation.

Some case setups are so bad that the temperature in the case is 20degC about the ambient air temp, add dust clogged heatsinks and vents and you can get into the extreme end of things fast, that's how people cook their PCs.

Do you know what the boiling point typically is, for PC heatsink heat pipes? It seems like there should be a nonlinear bump in cooling efficiency, as you cross this threshold. If one did a careful test of power vs. temperature, there should be a distinct uptick, especially on coolers with just a couple heat pipes.

It's tuned by the manufacture, the working fluid is typically distilled water or alcohol or a mix of the two, sealed under a part vacuum to lower the boiling point, the fluid mix and the vacuum pressure can be changed to tune the boiling point to the desired operating temperature. It one of those trade secrets, but it's probably in the 30-40 deg range, with the heatsink relying on standard conduction at lower loads.

 

[bit_user]

The Coolermaster direct touch relies on the CPUs IHS to spread the heat across the heatpipes, but the IHS isn't the ideal thickness to spread the heat efficiently,

Yes, one possible explanation I considered.

so the direct touch heatsink preforms worse if mounted with the heatpipes mounted parallel with the die vs across the die. The uneven surface would destroy a CPU in direct die application.

Agreed.

Cooler master did it on their V8 series of desktop coolers, but they cost as much as a cheap 240 AIO, with worse performance.

Someone also made a 3D vapor chamber with 2x 120 mm fans side-by-side. I forget the name, but I recall it weighs a ton.

Some case setups are so bad that the temperature in the case is 20degC about the ambient air temp, add dust clogged heatsinks and vents and you can get into the extreme end of things fast, that's how people cook their PCs.

Windows don't help, either. It's too bad anodized aluminum is no longer trendy. I have a set of Lian Li windowless aluminum cases (with dust filters) I'll probably keep as long as I continue building my own PCs.

it's probably in the 30-40 deg range, with the heatsink relying on standard conduction at lower loads.

It would have to be far enough above ambient that you'd always be able to condense it with heated case air. So, my bet would be in the realm of 50 - 60 degrees C, in order to avoid the breakdown scenario you outlined, where the fluid converts fully to gas. That said, the more of it boils, the higher the vapor pressure and thus the boiling point should rise - perhaps not by much, but it should give some range between when the heatpipe starts to work efficiently and when it stops.

 

[das_stig]

Dropping 20c shows how inefficient todays IHA and TIM used by manufacturers are and they need to improve there development.

 

[TerryLaze]

Dropping 20c shows how inefficient todays IHA and TIM used by manufacturers are and they need to improve there development.

Intel can't sell these as 6Ghz all core though because not all of them will be able to do that, their cooling is focused on the actual product that they can produce and sell and not on an extreme overclock that might be stable enough, or might not be.

 

[thestryker]

The delidded temperature drops are why I wish Intel/AMD would be willing to sell a line of CPUs without IHS. While I wouldn't use liquid metal personally a phase change pad or one of the graphene pads should still get most of the advantage. All of the delids Roman has done show a bit of power consumption reduction on top of the temp for both Intel and AMD CPUs.

EK has a direct die AIO which has a pretty big benefit over using an AIO with IHS so it isn't limited to just custom loops. It would be really interesting to see if an air cooler with a vapor chamber would have similar benefits.

 

[taz-nz]

Dropping 20c shows how inefficient todays IHA and TIM used by manufacturers are and they need to improve there development.

A lot of the temperature difference is caused by number of different materials layers the heat has to traverse and the total thickness of those layers combined.

In stock config the heat conducts through:
The silicon of the die.
The indium solder.
The copper IHS. (I'll ignore the super thin nickel plating)
The thermal interface material.
The copper of the water block
To reach the water to be conducted away.

Delidded in a direct die water block config, the heat conducts through:
The silicon of the die.
The liquid metal thermal interface material
The copper of water block.
To reach the water to be conducted away.

But that's not all, the thinner each layer is the less thermal resistance there is, so while liquid metal thermal paste is slightly less conductive than indium solder, the layer is much thinner so allows more heat transfer, the copper of a direct die water block can also be thinner, as it doesn't need to resist the bending force cause by mounting pressure required in stock config.

There is very little CPU manufactures can do to improve the thermal transfer of the stock config, without going back to naked dies like we had in the late 90s early 2000s, when people would chip or shatter their CPU die installing a heatsink.

 

[Amdlova]

Direct touch heat pipes its a nightmare...
Need to put a whole thermal paste tube to fill the gaps and heights of the base.
I see some people making cooper pipes with acetone start boil at 50°c and goes critical at 250°c

(long time ago need to remove the ihs from a atlhon x2 with stock cooler have drooped almost 20°c.)

 

[taz-nz]

The delidded temperature drops are why I wish Intel/AMD would be willing to sell a line of CPUs without IHS.

They learn the lesson that consumers can't be trusted with naked die CPUs back in the socket 370 Pentium 3 and early Athlon days, AMD actual had a protective can on the K6 series CPUs and removed in on the Athlon for better thermals only for it to return to a modern IHS with the Athlon 64.
People cracking their CPU was fairly common, the IHS also gives the onboard thermal sensors a little more time to save the CPU before localized heating cause the die to fail if a heatsink is not installed.

 

[thestryker]

They learn the lesson that consumers can't be trusted with naked die CPUs back in the socket 370 Pentium 3 and early Athlon days, AMD actual had a protective can on the K6 series CPUs and removed in on the Athlon for better thermals only for it to return to a modern IHS with the Athlon 64.
People cracking their CPU was fairly common, the IHS also gives the onboard thermal sensors a little more time to save the CPU before localized heating cause the die to fail if a heatsink is not installed.

That was the era I learned about PCs and really started tinkering and putting them together. None of my friends group ever saw a cracked die between us we dealt with around 100 or so, admittedly a small number, PCs with exposed die. Most of the cracked die were caused by overtightening coolers which is very easily engineered around.

With how small the compute die are getting and how much power both AMD and Intel are pumping through them something is likely going to need to change (I doubt power consumption is going down). Given that AMD had already tested a vapor chamber IHS (sounds like cost killed it) the question is will we see vapor chambers or naked die.

 

[taz-nz]

That was the era I learned about PCs and really started tinkering and putting them together. None of my friends group ever saw a cracked die between us we dealt with around 100 or so, admittedly a small number, PCs with exposed die. Most of the cracked die were caused by overtightening coolers which is very easily engineered around.

I worked as a service tech for a PC and parts retailer back then, the service team would repair 300-500 PCs a week, and cracked dies were a thing, so much so you could buy cooper shims to protect your Athlon XP.

The most common causes were people trying to scrape off old dry thermal interface material with a hard object (still a common cause of damage on laptops and GPU dies, and people mounting the heatsink backwards on the socket, the retention clip for Socket 370 and A heatsink were asymmetric and putting the heatsink on backwards would apply all the pressure along one edge of the CPU die.

A quick google search for cracked or chipped CPU or GPU die, you'll find it's still a common issue with people miss handling naked dies.

 

[thestryker]

The most common causes were people trying to scrape off old dry thermal interface material with a hard object

It seems absolutely crazy to me that people try to do it that way and it'd never even cross my mind that this is a thing. I don't even use anything hard on CPUs that have an IHS and certainly never even considered on GPUs. I guess there's no end to the lack of thought people apply when doing things.

A quick google search for cracked or chipped CPU or GPU die, you'll find it's still a common issue with people miss handling naked dies.

GPUs I've seen quite a bit about (usually tension related) and CPU delidding gone wrong, but I haven't really seen much regarding laptop CPUs (the only class of CPU currently sold bare).

 

[taz-nz]

GPUs I've seen quite a bit about (usually tension related) and CPU delidding gone wrong, but I haven't really seen much regarding laptop CPUs (the only class of CPU currently sold bare).

Damaged chips in laptops are a little less common, probably because anyone lacking care will find a dozen other ways to damage or destroy a laptop before getting it disassembled far enough to get to the naked dies. But I've seen damaged laptop CPUs and chipsets, and heard of damaged GPU dies, again lack of care remounting heatsink or cleaning dies of old thermal material are the typical causes.