This video seems to be about LM on untreated copper (which I thought wasn't really advised).

Now, I personally have had two builds with LM. One with LM as the material for a CPU re-lid, and another for a direct-die application. Neither touched aluminum or untreated copper.

The re-lidded CPU is still going strong, no issues. But with the direct die application, I found the performance to significantly degrade after two years. Apparently there's a pump-out effect.

I ended up switching to PTM. Same temps as LM, but zero degradation so far.

▲

badlucklottery 2 hours ago | parent | next [-]

> LM on untreated copper (which I thought wasn't really advised).

I think the supposed issue is nickel (the most common waterblock coating) has a much lower thermal conductivity so you might lose a degree or two under load vs a bare copper block.

Which kind of makes sense: people who know what they're doing use liquid metal to squeeze out that last couple degrees vs PTM/graphene so going bare copper and dealing the the buildup problems maybe makes sense for them too.

He mentions in this video that liquid metal really should just be for the extreme overclockers who don't mind changing it out and resurfacing their waterblocks regularly which is good advice. The fact liquid metal is even semi-mainstream and comes standard on any consumer hardware is kind of stupid.

▲

paimapi 2 hours ago | parent | prev [-]

I never really understood why you would risk using liquid metal versus something like Honeywell's PTM with the effect size in temperature difference indistinguishable from statistical noise. The only drawback I've seen for the PTMs is that the paste is extremely sticky to the point that I've ripped pins off an old 3600 when I tried to remount the cooler without warming it up first.

▲

Scene_Cast2 an hour ago | parent | next [-]

That's what I had lying around when I started the build. PTM is now my go-to recommendation.

▲

mindslight an hour ago | parent | prev [-]

From what I've seen the whole PC review industry operates on emotional narratives rather than scientific measurements. When is the last time you saw a cooler spec'd by its thermal conductance (Watts per degree C) as opposed to a whole rigamarole of we used so and so RGB motherboard with so and so PC case and this version of Windows with so and so benchmarking software. And every cooler in the limited set we compared it to was worse, but of course we left a whole bunch out. Like sure integration testing can be useful, but it doesn't beat characterizing units in isolation with hard numbers. And they never reduce the number of variables enough to do that.

▲

jmb99 an hour ago | parent [-]

Part of the problem is that any given cooler doesn’t have a single W/K value. It depends on the temperature gradient across the heatsink which depends on airflow over the heatsink (and both the heat and heat density of the CPU being cooled), and the airflow depends on the case (and fans). And airflow temperature matters too (are you cooling the CPU’s heatsink with air that’s already been warmed by a GPU?)

Note as well that I said heat density - different benchmarks (or applications) will load the CPU differently, and the same amount of power consumption will result in very different heat outputs (heavy single core use will result in part of the die and heat spreader getting really hot, whereas heavy multi core use will result in the whole die and heatspreader getting kinda hot). If the heatsink has a very high surface area and high airflow it might have the ability to dissipate quite a lot of heat, but if the contact surface sucks (or is aluminum) it might not actually be able to transfer heat away very effectively without a massive temperature delta - resulting in high CPU temps for single core use even with a high cooling capacity for multi core use, for example.

Your average person can’t understand all of these variables, and the average reviewer can’t control for all of them. So, “this CPU with these benchmarks in this case with this fan configuration” is the best you can really expect. Because otherwise, what reporting are you actually going to do? “This cooler with 3.2CFM of 26C airflow on a CPU dissipating 80W on one core and 10W on the other 7 cores results in a peak core temperature of 87°C and a package temperature of 81°C” is not useful reporting. Especially because, when the average person doesn’t understand it, they’re gonna buy a case fan that says 3.2CFM on the box and then wonder why their CPU’s throttling.

	▲	mindslight 29 minutes ago \| parent [-]
		Sure, but the goal of science is to distill these variables down into a model of what matters. Define a reference contact patch that's supplying the heat, and you've suspended all of the concerns about single core vs multi core. Then for more in depth articles, there could be a few to represent single core (smaller area), multi core (consumer processor), and multi core (larger server packages). Same with the airflow over the secondary parts of a cooler. Another in depth article could then even analyze CPUs and how they themselves differ from that reference contact patch, and their own thermal resistance from each core to their surface. And yeah, I know this is more work. The point is that doing the work allows the results to be used and compared across articles, even when some things are subtly different (eg contact patch). The problem is we're missing a strong incentive for that last bit.